Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Topics - sgottlieb

Pages: [1] 2 3 4
1
Observing Reports / Observing in Australia (Part II)
« on: Yesterday at 06:41:59 PM »
Over the five clear nights we had at the “Spring" OzSky Star Safari (ozsky.org), I logged over 250 objects, but the most astonishing vistas were certainly in the LMC.  In many single eyepiece fields, you find yourself gazing at a handful of emission nebulae, possibly a supernova remnant, and several clusters — some with resolved LMC stars and others unresolved knots — all superimposed on a bright, glowing background of the LMC itself!  The following is just of sampler of some of the LMC treats I observed during the week.  If this whets your appetite, you can download detailed descriptions and data on my favorite 8 “Showpiece Regions of the LMC" on the page of "Catalogs, Lists and Links” .

LMC-N59 Complex = Seagull Nebula = Dragon's Head Nebula (includes NGC 2030, 2032, 2035 and 2040)
05 35.4 -67 34.5
8’ diameter

Overall the visible structure of this complex using the 25-inch at 202x and 264 with a narrow-band filter, was comparable to the AAO-red image! (without the color, of course).

NGC 2030 is the first section in this remarkable complex (just off the upper right edge in the ESO image), though it was the faintest of three connected patches extending 5.5' from NW to SE with NGC 2032 and 2035.  The brightest portion is an elongated "bar" section ~2'x40", oriented WSW-ENE, just west of mag 12.2 HD 269810.  Fainter nebulosity spreads to the north in roughly an oval outline and includes a mag 14.5 star, so the total extent of NGC 2030 in the N-S direction is over 2.5'.  Very faint nebulosity appears to connect NGC 2030 with brighter NGC 2032 directly SE.

NGC 2032 was extremely bright, elongated SW-NE, ~2'x1', with a scalloped but sharply defined border at the brighter edge along the dust lane. A fairly prominent thin filament extends NE for ~1.5', curling a bit towards the tip.  A thin strip on the SE end (just beyond the lane) connects to NGC 2035.  The ionizing star was visible unfiltered at the eastern border, in an indentation, though it appeared fainter than the listed mag of 13.5.  A second mag 14 star was also involved at 25" to its east.  A mag 11.4 star is off the SW side and a mag 12.2 star is at the NE edge.

NGC 2035 was also extremely bright, roughly rectangular but irregular with slightly concave eastern side and lots of complex, internal structure with brighter and darker areas. A fairly thin streamer is attached on the northeast end and extends 2' NNE, similar (though slightly fainter) to a filament attached to NGC 2032!  NGC 2035 is attached or merged at the south end by a thin strip of nebulosity to NGC 2032. LMC-N59C is a fairly faint patch that is detached from NGC 2036 to its southeast.  It appeared moderately large, roundish, at least 1' diameter.  A mag 10.4 star is 2' ESE.

NGC 2040 appeared bright, very large, irregular nebula just east of NGC 2030/2032/2035 (Dragon's Head or Seagull Nebula).  The main portion is roughly triangular with one "vertex" on the south side and another on the northeast end.  It has a sharp, contrasty edge on the east side to the south tip and some internal, irregular brightness in the interior.  Unfiltered a dozen stars mag 14-15 are involved (association LH 88), with several more spreading to the south.

SNR B0536-67.6 is a supernova remnant shell on the south end of NGC 2040 and the objects are merged on the north end of the shell. Sometimes NGC 2040 itself is incorrectly called a SNR in the professional literature.  On images the shell extends ~2' in diameter, with a complex interlaced web of delicate filaments.  Visually, I could see a very faint, thin curving loop, ~45" in length, which forms the southwest end of the shell. A mag 13.5 star (O5-type) is in the interior of the shell, with the observed strip centered 40" to its WSW. This star was possibly bound to the precursor star of the SNR remnant.


LMC-N83 Complex (includes NGC 1737, 1743, 1745, 1748)
04 54 13 -69 10 40
Size: 12'

NGC 1743 = N83A is the overall brightest section of another superb HII/cluster complex including NGC 1737, 1743, 1745, 1748 and 1756.   Using 244x, along with a narrow-band filter, it appeared extremely bright, fairly large, irregular, extending ~1.5' NW-SE.  The most prominent section has a very high surface brightness and contains a mag 12.5 star.  This knot is surrounded by a fainter halo to the SE and E, along with an extension towards the NE that ends just south of NGC 1737 (nearly connected).  In the same nebulous complex (N83) is NGC 1748 ~2' NE, NGC 1745 3' NE, NGC 1737 2' NW and NGC 1756 5' SE.

NGC 1737 = N83C was fairly faint but moderately large, roughly 0.9' diameter.  A mag 14.4 star is at the center of the circular patch.  This tract of emission nebulosity is on the northwest side of the complex with NGC 1743 1.8’ SE.

NGC 1745 = N83D, on the northeast side of the complex, was also fairly faint, but easily seen as a fairly large, irregular nebulous haze, surrounding a half-dozen stars mag 14 and fainter.  Good contrast gain using a narrow-band NPB filter at 244x.

NGC 1748 = N83B is a fairly bright but fairly small round patch with a high surface brightness and a diameter of ~30".  At 397x, a 13th mag "star" was resolved at the southeast edge.  This star is classified as a high excitation H II “Blob" [HEB].  According to Iranian-born astronomer Mohammed Heydari-Malayeri , these unusual objects represent "early stages of massive stars emerging from their embryonic molecular clouds".  Unfiltered a second star (mag ~13.5) was seen closer to the center, forming a 7" double with the HEB.



NGC 2029 = LMC-N63 and LMC-N62
05 35 40.8 -66 02 06
V = 12.3;  Size 4'

I used the 30-inch to examine NGC 2029 at 202x, 264x and 429x, both with and without filters.  This is a large, fairly bright cluster (known as Shapley-Lindsay (S-L) 595) with roughly 30 stars resolved in a 3.5’ region. It includes at least 4 brighter stars from mag 12.3-13.5 and another mag 12.7 star is at the SW edge.  Moderately faint nebulous haze (LMC-N63) encompasses the cluster.  Adding a narrow-bandpass NPB filter at 264x increases the contrast with the large nebulous glow, which extended 2.5-3' diameter.  Note: this object is identified as NGC 2030 in most sources!

Henize N63A (discovered by Karl Henize in 1956), embedded slightly east of center, is a well-known compact supernova remnant and one of the first 3 extragalactic SNRs to be discovered (1966).  The SNR appeared as a small round knot, only ~12"-15" in diameter, and was faintly visible even at 202x.  It was easy to distinguish at 264x and stood out fairly prominently at 429x.  Surprisingly, I didn't notice any contrast gain adding a NPB filter (similar visibility).

Roughly 14’ SSW of NGC 2029 is N62A. I observed this HII region with a 14-inch using a NPB filter.  It appeared very bright, very elongated ~E-W, relatively large, ~1.5'x0.4'.  The shape is a bit irregular, but has a sharply defined northern edge, while the southern edge weaker and more ill-defined.  Visible unfiltered but excellent response to the NPB.  A couple of very faint stars are visible with averted.  BSDL 2348, an LMC cluster perhaps associated with the nebula, is ~2' W and contains a  half-dozen mag 14-15 stars in a 1.5' knot, along with a mag 12.5 star on the west end.



"Lionel Murphy" Supernova = LMC-N86 = SNR B0456-68.7
04 55 49 -68 38 30
Size 3.5'

In 1977, Mike Dopita, Don Mathewson & Vince Ford, working at the Mt Stromlo Observatory in Canberra, published a paper titled "Optical emission from shock waves. III. Abundances in supernova remnants.”  It included a photograph taken at the 150-inch prime focus [of the Anglo-Australian telescope at Siding Spring] that is labeled the "Lionel-Murphy" SNR.  Aussie Steve Mencinsky told me he was working as a night assistant at the time on the 74-inch at Mt Stromlo (later destroyed in a bush fire) in early 1976 as a "vacation scholar”.  One day a few astronomers were taking a break and looking at some of the prints of nebulae in the Magellanic clouds.  Steve looked at this SNR image and said "That looks like Lionel Murphy!”.  Who, you say?  Murphy was a politician, former Attorney General turned Judge of Australia's High Court, who is later life got mixed up in a corruption scandal — and apparently had a rather distinctive nose.  The Wikipedia page on Murphy (https://en.wikipedia.org/wiki/Lionel_Murphy) states ""Murphy normally rejected public honours (such as a knighthood) but accepted this [nickname] because of the symbolic resemblance to his own impact on human rights in Australian law and its lasting significance as a "signpost" to space travelers. Murphy asked for a large mounted photo of SNR N86 from the scientific paper and placed it in his High Court chambers in the place where the other High Court justices usually hung a portrait of the Queen.”

With the 25-inch (unfiltered) at 244x, this LMC supernova remnant appeared as a large, low surface brightness hazy region, just south of a mag 11.8 star.  A couple of 14th mag stars appear involved with the haze.  The mag 11.8 star forms the eastern vertex of an isosceles triangle with a mag 11.5 star 5.6' NW and a mag 10 star 6' SW.  There was a weak contrast gain adding a NPB filter, with the most evident section ~1' diameter [centered 1.2' S of the mag 11.8 star] and slightly brighter on the east side.

Images in H-alpha, [O III] and [S II] reveal a relatively well defined shell of over 3' diameter, rich in internal filamentary structure, and a large jetlike stream of filaments extending 2' further north that appear to break out into the interstellar medium.



NGC 2103 = LMC-N214C
05 41 40 -71 19 56
V = 10.8;  Size 3'x2'

This unusual nebulous cluster was observed using the 25-inch at 244x.  If found it a fairly bright, very large, roundish glow surrounding a central star (12.7-magnitude O2-type Sk -71°51) with a bright quasi-stellar knot at the north edge (that strange-looking pinkish Pac-Man object on the image above).  Increasing the magnification to 397x, at least 8 stars were involved with the nebula (part of OB-association LH 110), which was clearly elongated NNW-SSE (tapering on the SSE end) and brighter along a central spine.  The addition of a NPB filter at 244x produced an excellent contrast gain and the nebula appeared very bright with an irregular surface brightness.  The small knot at the north edge (a high excitation HII blob or HEB) was prominently visible.

The central “star” (and nearly centered in the ESO image above) is unusually hot and bright and has been resolved by the HST into a compact cluster of at least 6 components in a 4 arc-second region!  The HEB at the north edge is typical of small dense regions, usually "only" 4 to 9 light-years wide, that sometimes form adjacent to or inside giant H II regions and represent "early stages of massive stars (O-type) emerging from their embryonic molecular clouds.



LMC-N11 Complex = Bean Nebula
04 56 45 -66 24 36
Size 5'x3'

The Bean Nebula complex (LHA 120-N11) is the second largest stellar nursery in the LMC after the Tarantula Nebula.  I showed off this tasty piece of eye-candy treat to the other OzSky participants using the 30” at 244x and this inspired Tony Tanner to image the field above.  I’ve viewed this region several times and the following notes were taken through the same scope a few years ago.  The showpiece is certainly NGC 1763, which sits near the center of a stunning field of emission nebulae and clusters including NGC 1760 7' S, NGC 1761 3' S, NGC 1769 6.5' SE, NGC 1773 8' ENE and NGC 1776 11' E.  NGC 1763 is a very bright, very large irregular nebula, shaped like a kidney-bean or a fetus. The main body extends 5'x3', elongated SW-NE with a bulbous portion on the northeast side and an indentation (weaker nebulosity) on the south side.  Overall the surface brightness is very high, though uneven, and much fainter haze and filaments flow out from the Bean in most directions.  Within the main body, the nebula is brightest in a loop on the southwest side and secondly in a section on the northeast side.

Involved with NGC 1763 is a large cluster catalogued as OB-association LH 10 (the youngest cluster in the LMC-N11 complex), with roughly two dozen resolved stars.  This cluster includes a number of 12-13 mag stars (several of which are massive O3-type stars), many in an elongated 1' group on the southwestern side.  At the northeast edge is mag 11.3 HD 268726 and 45" further east is LMC-N11A = IC 2116, a high surface brightness knot of ~15" diameter.  Very faint haze at the NE side of NGC 1763 bulges towards N11A.  This compact, discrete object is also classified as an HEB (High Excitation Blob), distinguished by high excitation, small size, high density and tightly linked to early states of massive star formation. The surrounding field is rich in stars between the individual objects with some locally brighter patches of nebulosity.

NGC 1761 is a bright, large cluster sandwiched between the Bean Nebula (NGC 1763) to the north and NGC 1760 to the south.  There are roughly 80 stars mag 11 to 16 in a 3.5' irregularly shaped group over some background haze.  The stars are fairly even distributed except for a detached 1.3' group of 10-12 stars off the NW side.  Including this detached section, the overall size of this star cloud (association LH 9) is 5’ x 3.5'.  A close bright double star (h3716 = 10.2/10.9 at 5") is on the NW side of the main group.

NGC 1760 appears as a string of a half-dozen stars, nearly 2’ in length, over fairly bright nebulosity.  The emission haze is brightest just south of the string and extending to the west of the string a couple of arc minutes.  Irregular nebulosity also branches out to the south of the string for another 2' and involves a mag 12 star.  Another 2' string of N-S stars is on the west side of the haze.

NGC 1769 is a bright, large oval nebula oriented SW-NE, roughly 3’ x 2'.  At the center is a mag 11.5 star (Sk -66 41), with three mag 14-14.5 companions, the closest 15" SE.  A small, bright knot (~10" diameter) is embedded on the south side of the nebula, just 0.9' S of the central star.  Sk-66 41 was once thought to be one of the most single massive and luminous stars in the LMC but has been shown to be a very compact cluster with over a dozen components.  The companion to the SE (an O3-class star) is actually the ionizing source of the nebula.  The bright knot on the south side was also discovered to be a compact cluster of very faint stars in 1987 and is identified as HNT 1 in SIMBAD.

NGC 1773 is a fairly large, bright glow, elongated 3:2 ~N-S, 2.2’ x 1.5'.  On first glance, two brighter mag 12/13 stars are offset southwest of the geometric center and separated by 17".  But on closer inspection the more central star (0-type supergiant SK -66 43), resolved into a very close double. In additional a couple of fainter mag 15/15.5 stars are superimposed on the north side of the glow.  The nebulosity is slightly irregular in surface brightness and brighter along the rim, particularly on the southwest side.  This emission nebula is located at the northeast end of the Bean Nebula complex.

NGC 1776, located on the east edge of the N11 complex, is a moderately bright cluster, fairly small, well concentrated with a small bright core surrounded by a 50" halo.  A couple of extremely faint stars are just visible in the halo.


2
Observing Reports / Observing in Australia October 15-22
« on: October 26, 2017, 09:28:58 PM »
During the October new moon period I hopped on the 15-hour flight from SFO to attend the week-long Spring OzSky Star Safari (ozsky.org/spring.asp), which took place on the 6300 acre Markdale Homestead (https://tinyurl.com/yd9ju9q5), a 3 to 3 1/2 hour drive west of Sydney in the Central Tablelands (https://en.wikipedia.org/wiki/Central_Tablelands).  I know several TACos have participated in these fantastic star parties (this one was my 4th, out of a total of 8 pilgrimages to the southern hemisphere), but here's the background.

A group of Sydney amateurs, in conjunction with the Three River Foundation (3RF) Australia (www.3rf.com.au/) offer this twice-a-year event, with the main star party hosting 3 dozen or so attendees in the Fall (that's around March-April downunder) at Coonabarabran NSW, near the Warrumbungles National Park and the Siding Springs Observatory.  It's mostly attended by U.S. amateurs and I'd guess half are repeaters, who are itching for more of the same.  What's the draw?  If you've been to the southern hemisphere, you know it beats the north, hands down, in terms of open clusters, globular clusters, emission nebulae and the single most impressive external galaxy in the sky -- the Large Magellanic Cloud.  And experiencing the center of the Milky Way at the zenith (with typical skies ~21.8+ SQM) and the jet-black dark nebulae forming the Aboriginal "Emu in the sky" is flat-out jaw-dropping.

The locals, led by Lachlan McDonald and Tony Buckley, provide the telescopes -- ranging in size from 14.5" to 30" (that's me on the ladder of the 30" on the first link), equipped with Argo Navis and Servocats if you don't want to star hop in unfamiliar skies, as well as a collection of Televue eyepieces.  Really all you need to do to prepare is sign-up in advance, download some of their showpiece observing lists, pack your clothes and join the party!

Two years ago we had a very small, private event.  Only three Californians (John Hoey, Kemer Thomson and myself) attended the Aussie Spring event, which took place at Markdale -- a large working sheep ranch and country estate with a beautiful Heritage garden.  Last October there was closer to 16 attendees, including locals Bob Douglas and Dennis Beckley, but this year we were back to another small group with just 4 U.S. amateurs (a 5th dropped out at the last minute).  That matched the number of scopes that Lachlan carried to the site in his trailer -- two 18's, a 25 and a 30", a one-to-one ratio!  Lodging was in two stone guest cottages, built in the late 1800's.

In mid-October, the galaxy-rich constellations of Fornax, Pisces Austrinus, Sculptor, Phoenix and Horologium pass nearly overhead from Australia and eye-candy galaxies in Pavo, Dorado,  and Reticulum are well placed.  But Sagittarius is still higher than we see it from home, and once you get used to seeing the constellation's Teapot outline completely upside down, its easy to track down obscure globulars and even Sagittarius galaxies that would be difficult from home.  But the biggest treat for me is the LMC, as there is absolutely nothing remotely comparable in the northern sky -- as well as the magnificent globular 47 Tucanae, which must be seen to be believed at high power.

We were pretty fortunate with the weather - 4 straight all-nighters to start the week, then 2 nights of clouds, and a clear 7th night.  So, 5 for 7 overall and enough observing time to log about 250 objects.  I came prepared with a list of 300 deep sky targets, but a subset of 34 NGCs had a special meaning.  These were the only ones I had remaining to observe and record out of the 7840 entries in the 1888 New General Catalogue.  Not sure if the entire catalog (covering +89 to -89 dec) has been attempted or previously completed by other obsessed amateurs. This huge project been percolating a long time -- I've been slowly working on it (along with many others such as Hicksons, Arps, Palomar globulars, Flat galaxies, Abell planetaries, rich galaxy clusters, etc. etc.) for quite awhile -- 37 years to be precise!  And along the way, the instruments evolved from a 6" f/5 Edmund, C-8 Schmidt-Cass, 13.1" Odyssey I, 17.5" Sky Designs (early truss-tube dob), 18" f/4.3 Starmaster and 24" f/3.7 Starstructure, along with a little help from Jimi Lowrey's 48-inch  ;).

Four or five years ago I finished all the NGCs accessible from northern California (down to -40° declination), but there was still over 300 remaining far southern objects.  After a couple more trips to Oz that number was whittled down to 34, of which 32 were well placed this time of year (that's why I missed them a year and a half ago from Coonabarabran).  The final two would have to be caught low in the sky either at dusk or dawn, but I knew they would be doable.  But first a bit of background on the NGC...

Roughly 2500 deep sky objects in the NGC were discovered by musician-turned-astronomer William Herschel from England and another 1700 by his son John, at Slough, England and later the Cape of Good Hope in South Africa.  Their discoveries were made with 18.7-inch speculum reflectors -- roughly equivalent in light-grasp to a modern 14- or 15-inch.  The next largest contributors in terms of visual discoveries were Albert Marth (over 500 using a 48-inch speculum reflector on the island of Malta), Lewis Swift (over 450 galaxies from Rochester, NY and southern CA using a 16-inch Clark refractor) and Edouard Stephan (over 400 from Marseilles using a 31-inch silver-on-glass reflector).  The largest scope that contributed to the NGC was Lord Rosse's 72-inch Leviathan and the discoveries made with this scope go down to mag 16.5V.  Within the next few years after the publication of the NGC, the golden era of visual deep sky discovery would wind down as long-exposure photographic plates revealed thousands of dim galaxies beyond visual reach and which now have IC (Index Catalogue) designations.

During the first two nights I logged 33 of the remaining objects (mostly galaxies in Phoenix and Tucana) using the 25" f/5 Obsession, leaving only one target remaining for the third night -- NGC 2932 -- which is nothing more than a Milky Way star cloud in Vela that captured John Herschel's attention.  He called it "an enormous cluster of 1 deg or 1.5 deg, very rich in stars of all magnitudes, from 8m downwards, which merits registry as a sort of telescope Praesape.  It may be regarded as a detached portion of the milky way."  With so many more mouth-watering targets nearby, most amateurs would probably put NGC 2932 in the "Why bother?" bin. But this one was a little more special to me.

I tracked down the field after 3:00 AM on the third night using an 18-inch Obsession at 79x (1° field of view).  I looked up and noticed Orion was 50° up and of course, turned topsy-turvy on its head!  Sirius and Canopus, the two brightest stars in the sky, hovered at 60° altitude and dominated the eastern skies. Truthfully I didn't find the star field of NGC 2932 very exciting, but I carefully examined it and a 1/4 degree richer section caught my eye as appearing more cluster-like.  The next day I checked the online SIMBAD database and was pleased to find this collection was catalogued as the 1,694th Milky Way cluster in a 2012 compilation (https://tinyurl.com/yb37vzva). So perhaps a real cluster is actually embedded in Herschel's star field.

During the daytime we toured the property, panned for gold, and watched mobs of 'roos bounding across as the fields when we drove by (actually this was a serious road hazard whenever we returned to the estate at twilight) and closely examined some of the other natives (two attached).  A bit scary, though, was a visitor who slithered very close to the observing field in the late afternoon -- an Eastern Brown snake, the second most venomous in the world!  For some false sense of security, I took all of my notes that night (some highlights will follow) at the shelf on the top of a tall ladder, instead of my usual observing table  ;D



3
Observing Reports / Globular Cluster hunting -- in Barnard's Galaxy!
« on: July 28, 2017, 06:01:55 PM »
For the July new moon I observed for 4 nights in the White Mountains above Bishop (Grandview Campground at 8500 ft), just below the Ancient Bristlecone Pine Forest.  Our group included Paul and Debbie Alsing, Kemer Thomson, John Hoey (all from the San Diego area), Jimi and Connie Lowrey (from west Texas but drove from Florida) and bay area locals Carter Scholz and Rick Linden.  The weather turned out great and the Detwiler fire southwest of Yosemite didn't impact us, though I drove through the smoke in Yosemite to reach the site.  SQM readings were generally in the 21.6-21.8 range, though occasionally below 21.5.  The largest scope was Rick's 32", which nearly dwarfed my 24" Starstructure.

Instead of posting a long list of observations (I logged 125 objects), I'll mention just one -- a Sagittarius globular that actually resides in Barnard's Galaxy (NGC 6822).  Edwin Hubble was the first to investigate Barnard's Galaxy in detail in 1925 (http://cdsads.u-strasbg.fr/full/1925ApJ....62..409H).  His study included a table of 10 nebulous objects within Barnard's Galaxy.  Most of these turned out to be HII regions (including 2 great visual targets), but Hubble VII turned out to be the first confirmed ancient globular in this galaxy.  The location, though, creates a problem -- its a tiny 16th magnitude speck superimposed on the glow of the galaxy and a very nasty visual target.  I was successful observing it twice from GSSP back in 2010 with my 18", though it was quite challenging (barely non stellar and lost in a maze of other dim stars within the galaxy).  I figured that was the last GC I'd see in Barnard's Galaxy

Four new globular discoveries in this dwarf galaxy were announced in 2011 but these seemed too faint for visual targets.  Then in 2013 three more were identified (so the current total is 8 ) and globular #7 (coincidentally the same number as Hubble's object) seemed a reasonable target for my 24".  When I added it to my observing list, I had no idea what to expect as I've never read of amateur observations of these globulars. You can read the discovery paper at http://adsabs.harvard.edu/abs/2013MNRAS.429.1039H, where it's called SC 7 (Star Cluster 7)

SC 7 is in the outskirts of Barnard's Galaxy, 22' NE of the center of the galaxy and well outside the visual extent -- that makes identification much easier!  Once the general field was centered using the 6mm Delos (375x), both Jimi Lowrey and I were surprised to quickly notice a non-stellar glow without first examining an image of the galaxy.  SC 7 was faint in my 24-inch, but clearly non-stellar, roughly 6"-8" diameter and 15-16th magnitude.  The globular could be held steadily when we backed the magnification down to 282x and possibly had a brighter stellar nucleus.

If you're curious about the distance, Barnard's Galaxy is ~1.6 million light years away.  For comparison, the most distant Milky Way globulars are 300 to 400,000 l.y. away, so this one is at least 4 times that distance!  I believe an 18" scope should catch this object from a dark site, if you know the precise location.

-- Steve 



4
I plan to observe this upcoming week (July 18-22?), along with several other northern and southern California amateurs, at Grandview Campground at 8500 feet in the Pinyon Juniper slopes of the White Mountains, just a half hour paved drive from Big Pine into the Inyo National Forest.  It's roughly a 7 hour drive from Berkeley, but the skies can be magnificent.

If you're interested in more info, contact me at <astrogottlieb at gmail dot com>.


5
TAC Visual / Lake Sonoma OR from Saturday May 20th
« on: May 21, 2017, 01:52:49 PM »
I decided to go to head to Lake Sonoma yesterday afternoon (Saturday) as the predicted conditions were excellent.   Only two others showed up -- Matt Marcus and Shneor Sherman, which was surprising as this was the best weather in terms of temperature/humidity/wind, etc. that we've had in awhile.  It turned out to be a dark night with pretty good seeing.  I made a SQM reading of 21.45, which beats most locations close to the bay area, though the Milky Way wasn't that impressive, so the transparency wasn't ideal.

Unfortunately, we were interrupted for at least an hour and a half by a parade of cars/pick-up trucks that drove into the large Lone Rock lot every few minutes, apparently looking for the rowdy party that took place in the equestrian area just below Lone Rock.  There was also an unusually high amount of road traffic on Rockpile Road, so not a very relaxing evening.  Around 12:30 it finally quieted down and fortunately stayed that way.

One highlight was the type IIP supernova SN 2017eaw in NGC 6946 -- the appropriately named Fireworks Galaxy, which was discovered a week ago on May 14th.  It was easily visible (close to mag 12.5) in the halo of the galaxy, 1.0' west and 2.4' north of the center, and formed a wide pair with a fainter star.  This is the 10th supernova in the past century in the NGC 6946 (I believe I've viewed 4 of these) and it holds the record for the most prolific SN producer: SN 1917A, SN 1939C, SN 1948B, SN 1968D, SN 1969P, SN 1980K, SN 2002hh, SN 2004et, SN 2008S, and now SN 2017eaw.  It may still be on the rise -- in any case it was easy to see in Matt's C-8 and certainly a 6" (or smaller) will do the trick.  Check it out if you view in the next week!!

I also viewed Comet C/2015 V2 (Johnson) in Bootes, which was a bright 7th magnitude (visible in binoculars) and displayed a faint but obvious tail that extended through much of the 13mm Ethos eypeiece field.  It displayed a large coma and an intensely bright nucleus.  This is easy to find and well placed mid-evening, so another one not to miss.

As far as deep-sky objects, I took notes on about 3 dozen galaxies -- mostly working on two projects.  One is to pick up very faint companions to NGC galaxies.  The companions are sometimes in the IC, but often just carry a PGC designation.  The other project is galaxy mergers -- where two nuclei can be resolved within a single common halo.  A good example is NGC 5259, a faint galaxy in Canes Venatici, which I viewed around 1:30.  The second nuclei, labeled in this image as Holmberg 533B (Eric Holmberg studied double galaxies as part of his doctoral thesis in Sweden in the 1930's), was tough at 375x but definitely visible most of the time.

6
Observing Intents / OI - Lake Sonoma Saturday 5/20
« on: May 20, 2017, 05:24:20 PM »
I'll be at Lake Sonoma's Lone Rock tonight at sunset for perhaps the last good look at Spring galaxies as they start to slip into the western sky and become less convenient to view.

7
TAC Visual / Action on Jupiter
« on: May 03, 2017, 07:58:29 PM »
With the moon now dominating the early evening skies, I've been doing a little Jupiter gazing in my driveway.  On Sunday night, Europa starting transiting the disk of Jupiter around 11:30 and last night (Tuesday) it was Io's turn.  It reached the limb around 10:00 PM and after 10:30, its shadow started marching across the face of Jupiter along the north equatorial belt.  This last sequence of events repeats next Tuesday, though a bit later.

8
Observing Reports / Springtime galaxies...observations
« on: April 06, 2017, 02:46:30 PM »
Here are my 10 favorites from last Tuesday night's observations.  Images (except for the Hydra I cluster) are from the Sloan Digital Sky Survey (SDSS).  The last image of the overlapping pair NGC 3314 is from the HST, of course.

Steve
------------

IC 2207
07 49 50.9 +33 57 44
V = 14.2; Size 2.0'x0.25'; PA = 124°

This member of the Flat Galaxy Catalogue appeared as a very faint, extremely thin ghostly streak, over 10:1 NW-SE, ~1.1'x0.1’, with a low fairly even surface brightness. It increased in length with averted vision, so the outer tips were a bit fainter. A mag 15.5 star is 30" NE of center.




IC 491
08 03 55.0 +26 31 14
V = 14.9; Size 0.6'x0.25'; PA = 114°

I took a look at this close galaxy pair at both 260x and 520x. The brighter eastern galaxy appeared faint, small, round, 12" - 15" diameter, quasi-stellar or stellar nucleus. Situated within a N-S string of mag 9 to 10.5 star including a mag 10.2 star 1.5' NW. IC 491 forms a very close pair (non-physical) with PGC 1779405 0.5' NW. This 16th magnitude galaxy appeared extremely faint and small, 6" diameter, only occasionally pops. The nearby bright star made the detection difficult.




IC 496 = IC 2229
08 09 44.2 +25 52 54
V = 14.6; Size 0.55'x0.3'; PA = 30°

IC 496 was resolved into a close pair (physical), separated by just 19" E-W. The brighter western component (IC 496A = LEDA 93095) appeared faint, very small, round, 10"-12" diameter. The fainter eastern galaxy (IC 496B = PGC 22903) was very faint, extremely small, round, 6" diameter. An 18" pair of mag 13.5/14 stars lies 1.5' SSE. Located 7' WNW of mag 6.4 13 Cancri (K0-type).




IC 480
07 55 23.2 +26 44 36
V = 14.2; Size 1.7'x0.3'; Surf Br = 13.4; PA = 168°

This edge-on appeared fairly faint, moderately large, very elongated 6:1 NNW-SSE, 0.9'x0.15', slightly brighter core. Bulges very slightly but no nucleus seen. Situated in a busy star field with a mag 15.5 star 1.2' S (collinear with the major axis). A mag 10.9 star lies 2.5' NW. This galaxy lies at a distance of ~200 million light years, which implies a true diameter of ~100,000 l.y. for the galaxy.




NGC 3067 + Quasar
09 58 21.1 +32 22 12
V = 12.1; Size 2.5'x0.9'; Surf Br = 12.8; PA = 105°

NGC 3067, about 70 million l.y. distant, appeared fairly bright, moderately large, elongated 5:2 WNW-ESE. The brighter elongated central section was mottled and appeared to have a sharp light cut-off (dust lane) on the northern flank. The eastern end of the galaxy has a lower surface brightness, probably due to dust.

3C 232 = Ton 469, a distant quasar with a redshift of z = .531 (light-travel time of 5.3 billion years), lies 1.9' due north. It was easily visible at 375x as a very faint mag 16 star. A brighter mag 15 star is 1.4' WSW of the quasar. This QSR was involved in one of Halton Arp's controversies. A neutral Hydrogen "bridge" appears to connect the quasar and NGC 3067. Arp proposed the QSR was ejected from NGC 3067, a theory which was rejected by mainstream astronomers.




Arp 174 = NGC 3068 + PGC 87670
09 58 40.1 +28 52 39
V = 14.3; Size 1.1'x0.9'; Surf Br = 14.1

NGC 3068 is the brighter of a close, interacting pair of galaxies with PGC 87670 just 36" SE (between centers). It lies in Leo, about 290 million l.y. distant. The NGC appeared fairly faint, fairly small, contains a small bright core, ~15" diameter. The oval halo has a very low surface brightness and extends ~25"x18" E-W. The companion was extremely faint, round, only 10" diameter at most. Although I couldn't hold this compact galaxy continuously (V = 15.6), it was often visible. There was no sign of a connection between the pair or the long, diffuse tidal tail to the southwest (lower right).




Arp 191 = VV 239 = UGC 6175
11 07 20.2 +18 25 52
Size 1.9'x1.1'

This interacting pair in Leo resides at a distance of ~375 million light years. The brighter and larger northeastern component (VV 239a) of Arp 191 appeared faint, small, elongated 3:2 ~N-S, 0.3'x0.2’.
VV 239b, just 20" SW, appeared very faint, round, just 8" diameter. There was no sign of the tidal tail to the east of VV 239a.




Arp 198 = VV 267 = UGC 6073
10 59 46.0 +17 39 10
Size 1.3'x0.9'

Arp 198 is an overlapping pair consisting of face-on spiral and a thin edge-on that extends right to the nucleus of the face-on. Halton Arp classified this pair under his category "Galaxies: Material ejected from Nuclei.” Clearly, he interpreted it as a face-on spiral with a jet extending to the west (right). But this SDSS image clearly reveals it as an overlapping pair very close to a star! There is no sign of distortion in VV 267a, so it is very questionable if they are currently interacting.

At 260x and 375x, the pair appeared as a very faint, fairly small, very elongated glow, ~0.4'x0.1', extending to the southwest of a mag 12.3 star. The faint glow had an unusual "spike" appearance, with a very small "knot" (core of VV 267a = UGC 6073b, the face-on spiral) at most 10" diameter at the northeast end close to the mag 12 star [28" SW of the star]. The spike or tail (VV 267b = UGC 6073a) extends southwest with the combined glow collinear with the star!




Arp 156 = UGC 5814
10 42 38.2 +77 29 42
Size 1.3'x0.8'; PA = 128°

Arp 156 is considered to be a gas-rich post-merger with a major-axis dust lane. This Draco galaxy is pretty distant at ~480 million l.y. It appeared fairly faint, moderately large, oval 4:3 or 3:2, contains a brighter core with much fainter asymmetric extensions ~40"x 30" NW-SE. The SE extension seemed cut off (due to dust?). A mag 12 star is 1.2' SW and a mag 10.7 star is 1.9' S. Also nearby is a mag 9.3 star (SAO 7190) 4.4' SW and a mag 7.8 star (HD 92319) 5.3' SSW. The view was significantly improved moving with these two brighter stars outside the field.




AGC 1060 = Hydra I Cluster
10 36 48 -27 32

I logged 19 galaxies in the central region of the Hydra I cluster — in preparation for an article in Sky & Telescope next year. This cluster is one of the closest fairly rich clusters to our Local Group, after the Virgo cluster, the Fornax cluster and the Antlia cluster. It has are some interesting similarities with the well-known Virgo cluster. The cluster is roughly 3 times the distance of the Virgo cluster and extends about ? the size in the sky — so both cluster have a similar linear dimension as well as a comparable number of members. Furthermore, both clusters have an giant X-ray emitting galaxy near the core — M87 in the Virgo cluster and NGC 3311 in the Hydra I cluster. Also like M87, NGC 3311 a huge number of globular clusters, estimated at ~16,000 GCs! It’s partner, NGC 3309, is also a giant elliptical but has a normal number of globular clusters — perhaps its retinue was stolen but its larger neighbor.

The cluster surrounds a naked-eye mag 4.9 star, which makes finding the cluster pretty easy in a dark sky, but also makes viewing some of the nearby galaxies pretty tough. Although ESO 501-047 was picked up pretty easily (I had previously seen this one with a 13-inch from Costa Rica, ESO 501-052 was pretty tough and of course the bright star had to be kept out of the field. A fascinating member is NGC 3314, near the bottom of the image above. It consists of two large spiral galaxies, which are directly overlapping! The dust lanes of the foreground galaxy are silhouette against the background spiral. Visually, though, only the brighter background galaxy is seen as the foreground galaxy has a very low surface brightness.

NGC 3314

9
Observing Reports / Springtime galaxies ...finally!
« on: April 03, 2017, 06:35:12 PM »
Last Tuesday (March 28th), with the new moon observing window starting to close, Mark McCarthy and I observed at Kevin Ritschel's ranch in the hills southeast of Hollister (Willow Springs).  The drive south from Berkeley in the afternoon was pretty brutal due to accidents and slowdowns and the usual 2 ½ drive took me an extra hour.  Still, I arrived about an hour before sunset and had plenty of time to set up my 24-inch and eat dinner while it was getting dark.  Mark arrived about a half hour after me and set up his 20-inch before I was finished.

About a half hour after sunset I started scanning in the west looking for Mercury but instead noticed an extremely thin arc, nearly lost in some low clouds and haze along the western horizon -- it was the crescent moon just 25 hours old!  Quite an exquisitely thin sight and totally unexpected.  About 15 minutes later I found Mercury, which was surprisingly bright and high -- both of us were initially unsure it was Mercury as it was so (relatively) high in the west.  But a quick look in Mark's scope (just a non stellar "blob") confirmed it was Mercury.  Turns out it was close to its maximum elongation (about 10° when we viewed it).

By 9:00 it was fully dark, but we could see some illuminated clouds along the western horizon and northern horizons.  Mark measured an SQM reading of only 21.2 or so (subpar for this site), but I believe it hit 21.5 or 21.6 sometime after midnight.  Early on we took a peek at comet 41P/Tuttle-Giacobini-Kresak near the Ursa Major/Draco border in Mark's scope.  This relatively bright and large comet seemed around 8th magnitude and contained a very prominent nucleus.  I also took a quick look at the planetaries NGC 2438 in M46 (Puppis) as well as NGC 2818A in the cluster NGC 2818 (Pyxis).  Neither of these planetaries are physically associated with the associated cluster.

I worked on three different programs in the evening -- each for a couple of hours.  First up was a number of IC galaxies in Gemini, Cancer, Canis Minor and Hydra.   The middle part of the evening was a survey of the central region of Hydra I galaxy cluster, which includes NGCs 3285, 3305, 3307, 3308, 3309, 3311, 3312, 3314, 3315 and 3316.  I took notes on 19 galaxies for a planned article in Sky & Tel next spring.  The cluster is a near twin of the downtown section of the Virgo cluster -- just 3 times as distant!  Late at night I focussed on a number of new (for me) Arp galaxies.  All in all, about 50 objects were viewed over 7 ½ hours.

One interesting galaxy was NGC 3067 in Leo, about 70 million l.y. distant.  The galaxy itself had lots of subtle structure -- logged as fairly bright, moderately large, elongated 5:2 WNW-ESE, mottled elongated central section with a sharp light cut-off (dust lane) on the northern flank.  The eastern end of the galaxy has a lower surface brightness, probably due to dust.  A very faint 16th magnitude star was easily visible 2' north.

This unassuming star is actually a super-luminous quasar (3C 232) at a distance of 5 billion light years and involved in one of Halton Arp's controversies.  A neutral Hydrogen "bridge" appears to connect the quasar and NGC 3067.  Arp proposed the QSR was ejected from NGC 3067, a theory which was rejected by mainstream astronomers.

10
TAC Visual / Colliding Galaxies
« on: March 17, 2017, 02:39:48 PM »
I wanted to mention I have a featured observing article titled "Galaxies in Collision" in the May issue of Sky & Tel, which should be out shortly (the digital version is already available).  It includes a number of interacting Arp pairs including the Antennae (cover photo) and other interesting duos such as the Mice, the Tadpole, the Heron, the Grasshopper and more.  Some of these are fairly well known and others are pretty obscure.  If anyone would like more "info" on the article, let me know.



11
Registration is open for the 2017 OzSky "Southern Spring" star party in Coonabarabran ("astronomy capital" of Australia), which runs from October 15-22 (7 nights).  If you have any interest in observing in the southern hemisphere check out http://www.ozsky.org/spring.asp.  That's me on the ladder of a 30" in SQM 21.8-21.9 skies.

I'm planning to attend again (this is my 8th trip to Australia!), as this is a remarkable opportunity to see the Magellanic Clouds and more.  All equipment is provided (mostly 18" to 30" scopes) -- you basically just have to show up and enjoy the dark skies.  A number of bay area amateurs have participating in OzSky star parties including Bob Douglas, Peter Natscher, David Cooper, Dennis Beckley, James Webster.  If anyone has any questions or possible interest, let me know.

12
Observing Reports / Blazers, Seyferts, Double Rings from Lake Sonoma
« on: January 06, 2017, 12:42:18 PM »

On two consecutive Wednesdays (21st and 28th of December) I observed under clear skies at Lake Sonoma, located 30 miles north of Santa Rosa just above numerous Sonoma county vineyards -- this is the Lake just before crossing the bridge along Rockpile Road.

On both evenings we had small groups at the Lone Rock lot, in the hills above the lake (the photo was taken as I arrived on the 21st). The first Wednesday I was joined by Bob Douglas with his 28-inch f/3.7 Starstructure and Carter Scholz with a homemade 16-inch with Zambuto optics. Conditions were excellent - perfectly clear, fairly good transparency for this site (SQM readings hit 21.4 by 11:00 PM), perfectly calm with no dew. I returned on the 28th with Bob and we were joined by Mark Toney (20” Teeter Dob) along with a friend. Again we had perfectly clear skies with SQM readings in the 21.3-21.4 range and good seeing. Both nights we started observing around 6:30 and closed shop by 12:30 and over those 12 hours were very productive – I logged a total of 90 different objects in my 24-inch f/3.7 Starstructure. My observing list in included a mix of interacting and other unusual galaxies as well as a few galaxy groups and I’ve highlighted several of these below.

I started off both evenings by taking a look at the amazing blazar CTA 102, which at a redshift z = 1.037 has a light travel time of 8 billion years! Normally this quasar shines dimly at 17-17.5 magnitude, but is known to be an OVV — an Optically Violent Variable quasar. In the past couple of months it experienced a historic outburst reading reaching mag 12.7-12.8 when I took a look in November. It’s been fluctuating wildly in the past few weeks — on the 21st I logged it at mag 12.7 and was impressed that it was easily seen when I added an 8-inch aperture stop to my scope. But on the 28th it appeared at least a half-magnitude brighter than a nearby mag 11.7 star, so was certainly mag 11.1-11.3 and has now been glimpsed in down to a 50mm refractor. Wow!! When I later checked on the AAVSO web site, I found that several observers measured magnitudes in the 11.2 range, so my estimate was accurate. This latest incredible outburst is over 300 times brighter than its “rest” magnitude. I just noticed the Fermi Gamma-ray Space Telescope also recorded an outburst of 135 times its average gamma-ray flux on the 28th, making CTA 102 the brightest gamma-ray source in the sky.



NGC 309 + IC 1602
00 56 42.8 -09 54 50
V = 11.9; Size 3.0'x2.5'; Surf Br = 14.0; PA = 175°

This beautiful grand-design galaxy is one of the largest (diameter ~225,000 light years) and most luminous known spirals (absolute blue magnitude = -22.52). Even at a distance of 260-270 million light years it has a V mag of 11.9! In fact Arp used this galaxy as an example of a discordant redshift — he felt it was just too large for its redshift and mentioned that M81 could comfortably fit in between its gargantuan spiral arms. It also appears to be something of supernova factory, hosting 4 in the past 17 years: SN 2014ef, 2012dt, 2008cx and 1999ge.

In my 24” it was fairly faint but moderately large, roundish, fairly low but uneven surface brightness, contains a brighter core that increases somewhat to the center. I noted hints of spiral arms in the halo (slightly brighter arcs) — this was before viewing an image. A mag 12.5 star is 2’ NNE and mag 15 star is off the west side, 1.5' from center.

Nearby is IC 1602, which lies 13’ WSW. This galaxy is the brightest member of Abell Galaxy Cluster (AGC) 117 with a redshift-based (z = .055) distance of ~738 million light years. I noted IC 1602 as fairly faint, round, 20" diameter, slightly brighter nucleus. AGC 117 is one of the galaxy clusters in the Pisces-Cetus Supercluster, one of the largest known structures in the universe (see http://www.atlasoftheuniverse.com/superc/psccet.html)





Arp 54 = VV 453
02 24 00.9 -04 41 42
V = 14.2 / 15.9; Size = 1.0’x0.55’ / 0.4’x0.3’

Arp 54 is a little-known interacting pair at a distance of ~570 million light-years. It shows up in infrared surveys, as a radio source as well as an x-ray source, so it apparently is experiencing very vigorous star formation or perhaps has an obscured active galactic nucleus (AGN) — both signs of an interaction. Arp placed it in his classification of "Spiral galaxies with high surface brightness companion on arm”, though it doesn’t appear that the arm from the larger galaxy reaches the smaller galaxy. The edge-on to the south is not related to Arp 54.

Using 375x the larger galaxy (PGC 9113) appeared fairly faint, elongated 3:2 E-W, 30"x20", fairly low surface brightness, weak concentration. Its interacting companion PGC 9107 is just 0.9' WSW. It was a very small faint glow, only 12" diameter. Although it easily popped into view with averted I couldn't hold continuously. A mag 14.4 star is 0.5’ SW.





NGC 7805/7806 = Arp 112 = VV 226
00 01 28.4 +31 26 16
V = 13.3 / 13.5; Size 1.2’x0.9’ / 1.1’x0.8'; Surf Br = 13.2 / 13.2; PA = 47° / 20°

Arp 112 is an interacting triple system consisting of NGC 7805/7806, along with KUG 2359+311, a strange arc-like galaxy. NGC 7806, the galaxy in the middle of the image, is also a gravitationally disturbed system with a thin tidal tail to the north. It’s not known whether KUG 2359+311 (Kiso Ultraviolet Galaxy) is a pre-existing third galaxy or the remains of one of the other galaxies — it looks like a detached spiral arm to me.

Through my 24”, NGC 7805 appeared moderately bright (V = 13.3), fairly small, compact, very slightly elongated SW-NE, 25"x20", small bright core and even brighter stellar nucleus. Forms a similar pair with NGC 7806 just 50" NE. A mag 13.5 star is 1' west. Other than a different orientation, NGC 7806 (V = 13.3) is a visual twin of 7805. KUG 2359+311 was only marginally glimpsed in the 24-inch (V = 16.3), so I asked Bob Douglas if we could look at Arp 112 in his 28-inch. By bumping the power to 427x we were able to glimpse a small narrow glow in his scope.





Markarian 1018 = UGC 1597
02 06 16.0 -00 17 29
V = 13.9; Size = 1.0’x0.5’; PA = 0°

Visually, there’s nothing remarkable about this galaxy, which appears to be a coelesced merger of two galaxies. Using 432x I logged it as "fairly faint, slightly elongated N-S, 25"x20". Two 13th magnitude stars are 50" NW and 1.0' W and a mag 14.5 star is 1.0' ESE."

But astrophysically Mrk 1018 is quite unusual. It’s a Seyfert galaxy, a type of spiral with an active galactic nucleus powered by a massive black hole and whose spectrum contains emission lines from highly ionized gas. Type 1 Seyferts contain extremely broad optical emission lines indicating the nucleus contains hot gas near the accretion disc that’s moving/expanding at very high speeds. Type 2 Seyferts display only narrow emission lines, while Seyfert 1.5, 1.8 and 1.9 are intermediate cases. The two main classes are thought to reflect different activity levels of black hole feeding, though possibly the viewing angle of the accretion disc is a factor.

Historically, Mrk 1018 has been classified as a type 1.9 Seyfert. But in the 1980s, prominent broad lines appeared in the optical spectrum and it changed its classification to a Type 1 AGN. In 2006, though, it was announced that in the past five years Mrk 1018 has returned to its original state type 1.9 state (see https://arxiv.org/pdf/1609.04423v1.pdf). This second transition is thought to be due to a decrease in the black-hole accretion rate.





Arp 200 = NGC 1134 + UGC 2362
02 53 41.2 +13 00 53
V = 12.1; Size 2.5'x0.9'; Surf Br = 12.8; PA = 148°

Halton Arp placed NGC 1134 in his category of “Galaxies with material ejected from nuclei”. Probably he is referring to the “tidal plume” off the upper right end of the galaxy generally extending in the direction of UGC 2362, the chaotic blue galaxy to the west. These two galaxies have identical redshifts so likely experienced a “close encounter” in the past with the arm of NGC 1134 pulled out by gravitational tides.

At 375x NGC 1134 appeared fairly bright, elongated 2:1 or 5:2 NW-SE, ~1.2'x0.6', sharply concentrated with a bright core and fairly bright, sharp stellar nucleus. It was slightly brighter along the east edge with averted vision — probably the bright section of the eastern spiral arm on Rick Johnson’s image. A mag 13.6 star is 50" NE of center. UGC 2362, 7’ to the west, appeared faint, very low surface brightness patch ~20" diameter (probably the brighter central part of this Magellanic system). A mag 14.8 star is 0.8' S.





IC 1767
01 59 59.4 -11 04 44
Size 1.7'x0.6'; PA = 75°

At 375x I called this galaxy "fairly faint, moderately large, elongated 5:2 WSW-ENE, ~1.2'x.0.5', large brighter core, no sharp nucleus. The halo brightens slightly at the WSW edge - perhaps a knot in the galaxy?"

I was pleased when I checked later and found the PanSTARRS-1 image above clearly shows a small galaxy (identified as 2MASX J01595678-1104533 in NED), at the position I noted. Although this galaxy appears to be superimposed, I don’t know whether the companion is actually at the same distance (no published redshift) or possibly in front of IC 1767.





NGC 1713 group = LGG 120 = WBL 110
04 58 54.5 -00 29 20
V = 12.7; Size 1.4'x1.2'; Surf Br = 13.3; PA = 45°

NGC 1713 is the brightest in a loose galaxy group called LGG 120 or WBL 110 at roughly 200 million light years. The group includes NGC 1709 and several fainter UGC and CGCG galaxies. NGC 1713 appeared fairly bright, oval 4:3 SW-NE, 0.8'x0.6', gradually increases to the center. NGC 1709, just 2.7’ WNW, appeared fairly faint, elongated 4:3 SW-NE, ~0.4'x0.3', very small or stellar nucleus. A mag 12.3 star is 50" NW. The following members of the group were tracked down (offsets given with respect to NGC 1713). Only the two closest are shown on the SDSS image above.

CGCG 394-055, 7.7’ SW: Fairly faint, fairly small, slightly elongated ~N-S, ~20"x15", slightly brighter core. Forms a close pair with CGCG 394-056 1.3' NNE.

CGCG 394-056, 6.6’ S: Faint, very small, round, 12" diameter. A mag 13.5 star is attached at the southeast end. Mag 8.9 HD 31724 is 5' W.

UGC 3221, 24’ S: Fairly faint, thin edge-on 6:1 NNW-SSE, ~30"x5", even surface brightness. A mag 14.5 star is superimposed at the south end. A mag 9.2 star is 4.7' S as well as a nearby mag 9.9 star.

UGC 3214, 26’ NW: Moderately bright, fairly large edge-on 4:1 SW-NE, at least 1.6'x0.4'. Contains a bright, elongated bulging core and much fainter extensions.

CGCG 394-053, 21’ NNW: Fairly faint, fairly small, elongated 2:1 NW-SE, 30"x15”.





NGC 741 group
01 56 21.0 +05 37 44
V = 11.1; Size 3.0'x2.9'; Surf Br = 13.5

This group (called WBL 061) resides in Pisces at a distance of ~250 million light years and is dominated by the NGC 741/742 double system. NGC 741 has an unusually large halo, sometimes indicative of galactic cannibilism and if you look carefully there’s a small stellar like object immediately to the left of the nucleus of NGC 741. Perhaps a former companion that strayed too close and is now falling into the nucleus of NGC 741? NGC 741 has a extended X-ray halo reaching a distance of 19’ from its center. Furthermore, twin radio jets emerge from the nucleus of NGC 742 and spread into a larger lobe that encircles NGC 741.

Visually, NGC 741 appeared bright, moderately large, round, sharply concentrated with a small very bright core that increases to the center. The halo increases with averted to over 1’ diameter. A mag 11 star is 2.4' NW. NGC 742 is just 0.8' E of center at the edge of the halo at a projected separation of ~55,000 light years. This is a small galaxy but has a high surface brightness. It was moderately bright, round, 15” diameter. The following half-dozen galaxies are within 15’ of NGC 741 and share the same redshift.

CGCG 413-006 (often misidentified as IC 1751), 1.5’ NW: Fairly faint, very small, slightly elongated N-S, 0.3'x0.2', sharp stellar nucleus. The mag 11 star lies 1.4' W.

CGCG 413-002, 3.3’ SW: Fairly faint, very small, round, 12" diameter.

CGCG 413-001, 9.5’ NW: Very faint, very small, elongated ~2:1 ~E-W, 18"x9”. Once picked up could just hold continuously with careful averted vision.

CGCG 413-010, 11’ NNE: Faint, very small, irregularly round, ~15"x12".

UGC 1425, 12’ NE: Moderately bright, small, roundish, 18" diameter, high surface brightness, occasional sharp stellar nucleus. Increases a bit in size with averted.

UGC 1435, 15’ E: Faint, oval 3:2 SW-NE, 30"x20", very low surface brightness patch, no core or zones. Collinear with two 14th magnitude stars 2' and 3' E.





ESO 474-026 = Arp-Madore 0044-243
00 47 07.5 -24 22 14
V = 13.7; Size 1.2'x0.8'; PA = 175°

ESO 474-026 is a unique double-ringed galaxy with two perpendicular rings -- both an equatorial ring and a polar ring surrounding a central nearly spherical galaxy (the only component that was visible). It is thought to be have resulted from the major merger of two similar mass haloes. There is no nearby “hit and run” collider galaxy in the vicinity. ESO 474-026 is on a list of the most luminous galaxies (Cappi et al. 1998) and a strong source of far-infrared and CO emission. Its nuclear spectrum indicates active star formation.

Visually it appeared fairly faint, irregularly round, 25" diameter, very small bright nucleus with a stellar peak. The Redshift-based (z = .0527) distance is roughly 700 million years so I wasn’t expecting to see anything of the ring structures. But it was fun to contemplate this blazing beacon that shines at a relatively bright mag 13.7 over this vast distance.


13
Observing Reports / 8 billion light-year blazar ridiculously bright!
« on: December 29, 2016, 11:30:15 AM »
Last night (Wed, 12/28) we had a small group of 4 observers at Lake Sonoma including Bob Douglas (28" Starstructure), Mark Toney (20" Teeter dob) and my 24".

The highlight of the evening for me was the blazar CTA 102 (8 billion light years).  This is the 4th time I’ve taken a look — the first 3 times the magnitude was between 12.5 and 13.0, although I heard it had been acting erratically in the past week with some spikes in brightness.  Well, last night it was at least a half-magnitude brighter than a nearby mag 11.7 star, so certainly mag 11.1-11.3.  Wow!!  The "normal" magnitude of this quasar is roughly 17.5 so the latest outburst puts is over 300 times brighter.  I have never heard of ANY blazar this bright, let alone one this distant.  It's probably peaked and will decline after this point, but no one really knows.

We had excellent conditions -- perfectly clear skies in the SQM 21.3-21.4 range and good seeing.  I started getting cold and tired around 12:30 but at that point I had logged over 40 objects in 6 hours of observing.  Bye-bye, 2016!

14
Observing Intents / Lake Sonoma - Wednesday night! (28 Dec)
« on: December 27, 2016, 07:18:33 PM »
Sky conditions look excellent for Wednesday night.  I'll be at Lone Rock perhaps a half hour before sunset along with Bob Douglas.  Gotta check out the violently variable quasar CTA 102 again and catch some 8 billion year old light!

15
Observing Reports / Objects near and far at Lake Sonoma 12/21/16
« on: December 24, 2016, 11:32:35 AM »
On Wednesday night (21 Dec), I met up again with Bob Douglas (28-inch f/3.7 Starstructure) and Carter Scholz (homemade 16-inch with CZ optics) at our Lake Sonoma observing lot 30 miles north of Santa Rosa.  Conditions turned out to be excellent for this time of year - perfectly clear, good transparency (SQM readings hit 21.4 by 11:00 PM), perfectly calm and no dew at all.  At this time of year I was able to start by 6:30 and logged over 40 objects when I packed up at 12:30.

As we were waiting for the sky to fully darken, Carter noticed an iridium flare towards the north and later he saw a very bright satellite that initially we thought was the ISS.  It dimmed slowly like a satellite but headed in the wrong direction towards the southwest??  Later in the evening I was observing in Orion and noticed a slowly moving satellite in my field, which was tracking.  I knew immediately what this was -- a geosynchronous satellite -- and turned tracking immediately off so it would just sit there in the center of the field, while the stars zoomed by.  Very cool.

First on my agenda after seeing these naked-eye near-Earth objects was another look at the Blazar CTA 102, which was still in its mega-outburst mode at mag ~12.7 -- that's for a quasar at 8 billion light years. Easily seen even when I put an 8-inch mask on my scope.   In the middle part of the evening I focused on faint Arp galaxy pairs and logged 9 new ones in Cetus, Pisces, Aries, Eridanus and Orion.   I also observed two galaxy groups -- NGC 741 in Pisces (8 galaxies logged) and NGC 1713 with 5 galaxies.  I may put together an observing report later with more details.

I'm thinking of an encore session next Wednesday to end the year.

Pages: [1] 2 3 4