Galaxy NGC 5805 - case of mistaken identity

[DavidR100]

On Monday night (15th May) I was observing galaxies in northern Bootes, using the All Sky Edition of Uranometria 2000.0 as my trusty reference. My equipment was a 16" Dob with 14mm EP giving an FOV of around 30 minutes and a magnification of 130.  I was observing from a pretty dark location in North Wales.

Less than 2 degrees NW of star 47 is a quadruple of galaxies: NGCs 5794, 5797, 5804 and 5805.  These are all roughly  10 minutes from a star which is prominent in the eyepiece.  

With the star more or less centred in the FOV, the galaxies were faint but immediately apparent.  When I compared the observed shape of the galaxy group with Uranometria, I realised that something was amiss, namely I observed NGC 5805 to the west of the star, whereas the atlas showed it to the east.

I checked theskylive.com, which agreed with Uranometria. 

I then checked stellarium-web.org which showed the pattern that I observed, with NGC 5805 west of the star, whilst the galaxy to the east was actually PGC 214349.  Neither theskylive nor Uranometria showed PGC 214349.

So it appears that both Uranometria and theskylive.com mixed up NGC 5805 with PGC 214349.

This little piece of detective work appeared to exonerate my observations - which I was clearly pleased about - but it found fault with Uranometria, which I had always regarded as "the bible".

What does anyone else think of this mix up?

Has anyone else come across this case of mistaken identity with NGC 5805?

Attached are:

- Scruffy sketch from my observations log showing the galaxies with "x"s and the nearby star. To see in the same orientation as the other images, flip from right to left and top to bottom.
- Image from stellarium-web.org with NGC 5805 highlighted in red.
- Image of snippet of page 36 (left) of Uranometria showing the galaxy group and "NGC 5805" highlighted.
- Image from theskylive.com with "NGC 5805" circled in green.

 

Edited May 19, 2023 by DavidR100
Clarified the edition of Uranometria

[mdstuart]

I checked my notes and I could only see the three brightest galaxies.

There are a lot of issues like this over naming in the older catalogues. Some have even written books explaining all the issues.

Well done on spotting the galaxy regardless of its name!

Mark

[DavidR100]

17 hours ago, mdstuart said:

I checked my notes and I could only see the three brightest galaxies.

There are a lot of issues like this over naming in the older catalogues. Some have even written books explaining all the issues.

Well done on spotting the galaxy regardless of its name!

Mark

Hi Mark,

Thanks for your feedback.  I now remember reading online a few years ago about disagreements, some of which seemed quite personal, between authorities on the naming of some NGCs.  

It's a sobering thought that the well known atlases and planetarium software should just be treated as "guides" even for the long established catalogues.

David

Edited May 19, 2023 by DavidR100

[DavidR100]

On 18/05/2023 at 22:49, mdstuart said:

I checked my notes and I could only see the three brightest galaxies.

There are a lot of issues like this over naming in the older catalogues. Some have even written books explaining all the issues.

Well done on spotting the galaxy regardless of its name!

Mark

I still had a niggling doubt as to the correct location of 5805, so with the help of some links that I had squirrelled away a few years ago (probably from SGL or Cloudy Nights) I investigated further.

As a reminder, these are the coordinates I had already found for 5805:

                         RA                 Dec
Uranometria     14:57:11.6     49:37:43    
theskylive          14:57:11       49:37:40
stellarium-web  14:56:39.9    49:33:13.8

So stellarium-web has a different position from Uranometria and theskylive.

My investigation started at the beginning with J. L. E. Dreyer's original catalogue of 1888 [1] which had 5805 with an RA of 14.52.31 and Dec of 39.47.5.  5804 had the same RA, with Dec of 39.45.3, i.e. Dreyer recorded 5805 2.2 mins south of 5804.

The Revised New General Catalog (RNGC) by Jack W. Sulentic and William G. Tifft, published in 1973, was the first prominent modern-day attempt to correct errors in the NGC catalogue.  I was unable to find this catalogue online.

A subsequent clean up attempt of the NGC catalogue by Roger Sinnott resulted in NGC2000.0 published in 1988. An online version of this catalogue was created by SEDS (Students for the Exploration and Development of Space) [2] which gives RA of 14:55.9 and Dec of 49:43 for 5805.

Next should have been the catalogue from the NGC/IC Project, whose aim was to check and update the original catalogues, and was developed in the 1990s and 2000s, but there is currently no public access to its database [3].  However, Steve Gottlieb, who was part of that project, has published a draft restoration of the catalogue [4] which gives RA of 14:57:11.7 and Dec of 49:37:43.  

Steve, one of the most prolific of modern day observers, has recorded his own observations for every NGC; the coordinates in his notes for 5805 [5] are RA of 14:57:11.6 and Dec 49:37:44.  Steve also includes historical notes and modern catalogue discrepancy errors, which tellingly say that 5805 was miss-identified in the Revised New General Catalog as PGC 53381 and this error propagated into several reputable catalogues and atlases including NGC2000 and the first version of Uranometria 2000.0.  This is one of multiple mistakes that Steve pointed out in the RNGC.

Harold Corwin was one of Steve's colleagues on the NGC/IC project; his forte is the precise positions of objects and gathering historical notes on them, so Harold's data would be expected to carry significant weight.  In Harold's own NGC catalogue [6], he gives an RA of 14:57:11.9 and Dec of 49:37:41 for 5805.

Wolfgang Steinicke also participated in the NGC/IC Project, and he has since created his own catalogue, the Revised New General Catalogue and Index Catalogue which is based on the NGC/IC but contains many additional objects, 13957 in all [7]. For 5805, RA is 14:57:11.7 and Dec is 49:37:43. Wolfgang also produced a Historic NGC/IC catalog [8], which interestingly contains the exactly the same coordinates for 5805 as his Revised catalogue.

Conclusion

Here are the position data for NGC 5805 that have just been uncovered:

                                                            RA                Dec
1. Steve Gottlieb's draft restoration    
of the NGC/IC Project catalogue:        14:57:11.7    49:37:43
2. Steve Gottlieb's own observations:  14:57:11.6   49:37:44
3. Harold Corwin's catalogue:              14:57:11.9   49:37:41
4. Wolfgang Steinicke's catalogues:     14:57:11.7   49:37:43
5. Revised New General Catalogue:     N/A             N/A
6. SEDS online NGC2000.0:                  14:55.9        49:43

The NGC2000.0 data is an outlier being 2 mins in RA different from the rest. Since NGC2000.0 is based on RNGC and Steve Gottlieb explained that the RNGC contained a mistake regarding the identity of 5805, the position of 5805 given by NGC2000 is expected to be incorrect. The likely coordinates for 5805 are therefore RA 14:57:11.7 and Dec 49:37:43, give or take a few seconds.  Dreyer, in the original NGC catalogue, placed 5805 2.2 minutes due south of 5804. According to Steve Gottlieb's draft restoration of the NGC/IC Project catalogue, 5804 has RA of 14:57:06.8 and Dec of 49:40:08, which would place 5805 at approximately RA of 14:57:06.8 and 49:37:56, which is a very good match with the Gottlieb/Corwin/Steinicke coordinates.

Returning to the original post, these results vindicate Uranometria and theskylive and show the data from stellarium-web to be in error. The object I thought was NGC 5805 must have been something else.

Mark,  I'm sure you are already aware of much of the information I have presented here, but I hope that this very potted summary of the development of the NGC catalogue and the list of references below will be of interest to readers.  I certainly found this an illuminating journey of (re-)discovery.  

References:
[1] "A database of actual optical scans of the original New General Catalogue and Index Catalogues compiled and edited by J.L.E. Dreyer. The volume which was scanned, is a reprint of the original catalogue dated 1971". http://ngcicproject.observers.org/ngciccat.htm
[2] SEDS online version of NGC2000.0: https://spider.seds.org/ngc/ngc.html
[3] NGC/IC Project catalog: http://ngcicproject.observers.org/pubdb.htm
[4] Steve Gottlieb's draft restoration of the NGC/IC Project catalogue: http://ngcicproject.observers.org/NGC/
[5] Steve Gottlieb's own data: https://www.astronomy-mall.com/Adventures.In.Deep.Space/NGC 5001-6000.html
[6] Harold Corwin's data: http://haroldcorwin.net/ngcic/ngconly.txt
[7] Wolfgang Steinicke's Revised New General Catalogue and Index Catalogue (look for "Revised NGC/IC Data"): http://www.klima-luft.de/steinicke/ngcic/ngcic_e.htm
[8] Wolfgang Steinicke's Historic NGC/IC (look for "The Historic NGC/IC is available here"): http://www.klima-luft.de/steinicke/ngcic/Expl_Hist_NGCIC.htm

Edited May 23, 2023 by DavidR100

[DavidR100]

The final piece of the jigsaw (I hope!) is to identify what I saw through the eyepiece that might have been NGC 5805.  

I re-observed last Sunday (21st May) and the position of the faint fuzz perfectly matched the position of the double star shown highlighted below in stellarium-web.  I couldn't resolve the faint double, I could only see nebulosity. 

Actually, this is quite a good fit to my original sketch which shows the angle subtended by the lines to the unknown object and the one joining the three galaxies as more than 90 degrees, whereas the angle subtended for the galaxy marked as 5805 (but which isn't 5805 😃) is less than 90 degrees.

 

Edited May 23, 2023 by DavidR100