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Messages - sgottlieb

Pages: [1] 2 3 ... 8
1
NGC/IC Project / Re: Corrected NGC v0 online
« on: April 26, 2017, 10:13:02 PM »
I don't believe the NGC/IC Project site ever had labeled images of the IC objects -- or at best a very limited subset.  That said the basic data is available, along with Harold Corwin's identification notes and my visual notes on over 1000 IC objects.

I'll confer with Corwin as well as Akarsh on the easiest way to grab that data.

2
TAC Visual / Re: Colliding Galaxies
« on: April 19, 2017, 10:22:24 AM »
Thanks, Marko.  Once again, if anyone without a subscription to Sky & Tel would like to see the article, just let know.

3
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

4
Observing Reports / Re: Rustling up some galaxies at the ranch
« on: April 05, 2017, 04:43:10 PM »
Must have something to do with our focusers being on opposite sides of the scope  ;D

Hickson 48 is one of those oddball cases of a supposedly isolated group (one of Hickson's criteria) being situated not far from the central region of a moderately rich cluster.  Maybe he made an exception to reach an even 100 groups.

5
Observing Reports / Re: Rustling up some galaxies at the ranch
« on: April 05, 2017, 11:13:00 AM »
Great report, McMark!  Fun to relive the night.

Your comment about NGC 3705 appearing to have a double nucleus piqued my interest as I've been making NGC galaxies with double nuclei (post-merger coalesced pairs) an observing project.  I've attached the SDSS image -- it turns out you noticed a very faint star just northwest (upper right) of the nucleus.  Nice catch.

I also wanted to mention that IC 2597 is also the brightest galaxy in the Hickson 48 quartet.  This is another one that was John Herschel overlooked in his sweeps.  Since he found all the other bright galaxies in the cluster (including much fainter NGC 3307), it's surprising he didn't catch this one, but it was probably just outside the limits of the sweep.  Lewis Swift was credited with the discovery in 1898 from Mt. Lowe (near Mt Wilson in the San Gabriel mountains), but actually E.E. Barnard discovered it 8 years earlier with a 12-inch refractor at Lick.  Barnard didn't measure an accurate position or publish the discovery, but it's right there in his notebooks.  I had seen ESO 501-59 previously (HCG 48B) as well as 16th magnitude HCG 48C, but this is the first time I glimpsed the faintest member HCG 48D (B = 17.0, V = 16.0).  Not bad for -27° declination.

6
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.

7
Observing Reports / Re: Planetaries In Puppis
« on: March 29, 2017, 08:40:43 PM »
Excellent sketches, Peter.  Mark McCarthy and I were at Deep Sky Ranch last night and one of the first objects I looked at was NGC 2818A, another planetary superimposed on an open cluster (NGC 2818) in Pyxis. -- sort of a poor man's version of M46 and NGC 2438.

8
Observing Intents / Re: Observing Tuesday NIght?
« on: March 27, 2017, 06:31:20 PM »
I'm planning to also observe on Tuesday night -- either at Lake Sonoma (if the north bay forecast improves a bit) or else I'll head south to Fremont Peak or Deep Sky Ranch.

9
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.



10
Joe, my anecdotal experiences may not be the best predictor, but here's been my experiences on two trips that time of year --

In mid-October '15, I observed at the Markdale site, along with John Hoey and Kemer Thomson.  I think the forecast was looking pretty bleak the day I flew to Sydney, so I was surprised the first half of the first night was clear (perhaps 4 hours).  The next day (Sunday) it rained all night, so not a great start at this point.  But then we had 5 consecutive all-nighters with very little or cloud-free conditions.  So, I ended the week exhausted from the number of hours of observing (6 out of 7 nights).  I check my notes again and SQM readings were consistently above 21.8 with several readings between 21.9-22.0.  I believe the star party last October/November had similar luck with the weather.  Locals Dennis Beckley and Bob Douglas attended, though you probably would have to contact them directly for their experiences.

In early November 2010 I observed at Coonabarabran, which is further from Sydney (perhaps a 6 hour drive).  The weather prospects looked dismal the few weeks leading up to the star party with consistently cloudy conditions and rain throughout New South Wales.  But although there were clouds during the daytime, it cleared by sunset on the first 4 days of the star party and I got in quite a bit of observing under impressive skies (SQM readings generally 21.85-21.89).   But we had clouds/rain for the last 3 nights, so we ended up with 4 out of 7 clear nights.

So, yeah, there is a risk with clouds/rains but I've rarely (if ever) returned from a trip to Australia bummed out by the weather (say with over half the observing time missed due to weather).  Conditions are drier further in the interior or perhaps on the west coast, but then you're really on your own in terms of planning a trip, and would have to lug along your own equipment.

Also, if you haven't been to southern hemisphere before and are only planning a single trip, then I would recommend going to the March/April star party as you get the full Milky Way overhead experience with lots of great nebulae/clusters that you haven't seen before.

11
I'll have to check it out.  I'm not sure how I got hooked on it, but I've actually watched a Australian melodrama (at least 3 seasons) that takes place in the 1950's called "A Place Called Home".  Full of stereotypes, prejudice and an over the top villain.  Nothing to do with astronomy, though.

By the way, the October event has been moved to a country sheep farm (Markdale) about 3 ½ hours west of Sydney.  Beautiful location that I observed at a year and half back.  SQM readings consistently above 21.8!  I know there's still openings if anyone has had a desire to observe in the southern hemisphere.


12
Observing Reports / Re: Some doubles around Gemini
« on: March 05, 2017, 06:38:15 PM »
Well done, Mark!  I'm guessing you were just running up against the mag limit of your scope/sky.  Also for some reason I often find the fainter companion of a close unequal, double appears dimmer than its magnitude suggests.

My notes on a several of these pairs are appended at the end, but here are a few more 2" or closer pairs in Gemini you might want to look at another time --

∑899 = ADS 4991
06 22 49.6 +17 34 27
V = 7.4/8.0;  Size 2.2"
18" (1/28/12): tight 2" white pair just cleanly split at 175x in fair seeing.  Crisper view using the 6" mask.

∑932 = ADS 5197
06 34 21.6 +14 45 08
V = 8.1/8.2;  Size 1.7"
18" (1/19/08): well-matched tight pair that at 1.65" that is just resolved at 175x.  Easy at 225x in good seeing.
18" (1/3/04): excellent evenly matched pair of mag 8 stars at 1.7" separation.  Splits at 160x and cleanly resolved at 215x.  Tangent airy discs with 6" mask at this power but easily resolved.

∑1037 = O∑166? = ADS 5871
07 12 49.1 +27 13 30
V = 7.2/7.2;  Size 1.1"

18" (3/10/04): clean split with 6" mask even at 220x!  This is a perfectly matched white pair.  This binary has a period of 119 years and is just past maximum separation (1.1").
18" (1/3/04): very close 1.1" pair of equal mag 7 stars.  Clearly double at 160x but not cleanly split.  Nicely resolved at 300x and with a 6" mask two nearly tangent airy discs are just cleanly resolved at 300x!
18" (3/24/03): very close, evenly matched pair (white/white) at 1.1".  Clean split in good moments at 300x.

∑1070 = ADS 5999
07 21 21.9 +34 01 36
V = 8.6/9.3;  Size 1.7"
18" (1/19/08): tight 1.7" pair but just cleanly resolved using 175x.  At 450x, tiny airy discs were resolved when the seeing was steady.

∑1081 = ADS 6038
07 24 08.9 +21 27 28
V = 7.7/8.5;  Size 1.8"
18" (1/19/08): fairly close 1.8" white pair is resolved at 175x.  Upping the power to 450x gave a wide split with clean star images.
---------------------------------------

Eta Gem = Bu 1008 = ADS 4841
06 14 52.7 +22 30 24
V = 3.3-3.9/6.5;  Size 1.6"
18" (4/10/03): Eta Gem is a challenging mag 3.3-3.9 (variable)/6.5 pair at 1.6" (slowly increasing).  Very large mag contrast with a yellow/orange primary.  Excellent at 300x and easy at 435x in good moments.  Supernova remnant IC 443 is close following.

∑942 = ADS 5258
06 37 40.6 +23 38 53
V = 10.1/10.1;  Size 3.5"
18" (1/28/12): perfectly matched 10th magnitude pair at 175x.  Fairly close (3.5") and nicely split at 175x.  Located 4' NW of mag 6.7 HD 47086.

∑981 = ADS 5570
06 55 28.4 +30 09 45
V = 8.8/9.0;  Size 1.1"
18" (1/19/08): this 1.1" pair was barely resolved at 175x and cleanly split at 225x.  At 450x, tiny airy discs were resolved and well separated.  This binary has a period of 5343 years and is still closing.

18" (3/7/04): very close 1.2" pair but cleanly resolved evenly matched duo.  Used both the 6" mask and at full aperture with a 9mm Ortho (250x).  Current separation at 1.2" is close to minimum.  Closing since discovery in 1831 (3.7").

Ho 342 = ADS 5725
07 02 50.5 +13 05 22
V = 8.0/8.7;  Size 1.2"
18" (1/19/08): very close 1.2" pair cleanly resolved at 300x.  Superb in good seeing at 750x with small airy discs.

∑1014 = ADS 5770
07 05 44.9 +26 08 25
V = 9.9/9.9;  Size 2.0"
18" (1/28/12): excellent perfectly matched 2" pair at 175x.  Cleanly split at this power but very close.

Weisse 14 = ADS 5875
07 12 48.2 +15 10 42
V = 7.8/8.9;  Size 2.1"
18" (1/19/08): this excellent 2" pair was just resolved at 175x and was beautiful at 300x.  Subtle colors.

∑1116 = ADS 6180
07 34 32.0 +12 18 17
V = 7.8/8.6;  Size 1.7"
18" (3/10/04): striking pair at 220x with the 6" mask.  Easily resolved at full aperture at 1.7".

∑1147 = ADS 6394
07 50 19.7 +24 31 56
V = 9.7/9.7;  Size 2.2"
18" (1/28/12): perfectly matched 2" pair just cleanly split at 175x.  Very similar appearance to ∑1014 = 9.9/9.9 at 2.0" observed a little earlier in the evening.

13
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.

14
TAC Visual / Re: Double Star Epsilon Canis Majoris
« on: March 03, 2017, 09:18:07 PM »
Mark, here are two observations I've made.  I've split it in both 6" and 8" apertures -- even at a low elevation if the seeing was good.  I don't have a good quality small refractor, but I'm sure it can be resolved.  So, Wikipedia is certainly wrong.

6" (2/19/07): mag 1.5 Adhara is a challenging double with a 7.5-mag companion at 7.5" separation.  It was cleanly resolved in moments of steadier seeing (viewed at 15° elevation) at 175x using a 6" mask.

C8 (seen several times in the early 1980's) : difficult pair due to very large mag difference.  Visible with at least 100x and fairly easy at 165x in excellent seeing.

15
Observing Reports / Re: Dinosaur Point what a night, 23 February
« on: March 01, 2017, 02:20:51 PM »
I'll throw in my notes of NGC 2467 from Costa Rica on 30 Jan '06 using Ray Cash's 13.1" travelscope.  It looks like Jamie also observed it the same month from Dino, though methinks he may have the wrong day of that month.

Bright, large nebulosity at 75x using an OIII filter, ~4-5' diameter, surrounding a mag 7.5 star.  The main section is roughly mushroom shaped, extending generally south of the bright star.  The southern border is locally brighter along a strip oriented NW to SE.  There is a sharp light cut-off (apparently due to dust) passing to the north of the central star and oriented E-W.  Faint haze extends ~15' to the east.  To the north, fainter nebulosity extends 12' E-W, and brightens towards the east end at an elongated group of brighter stars (Haffner 18), oriented NW-SE.  Removing the filter this is a gorgeous low power Milky Way field with numerous faint stars peppered in the region of the nebula.

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