View Full Version : NGC 1073 A face on barred spiral

2012-Sep-20, 02:52 AM
NGC 1073 is a nearby barred spiral in Cetus about 1.4 degrees north of M77. It is about 45 to 50 million light-years distant as best as I could determine. Redshift gives the shorter distance and the one Tully Fisher measurement I found gives the longer estimate. It is classed as SB(rs)c by NED and SBc II by the NGC Project.

NGC 1073 reminds me of Arp 38 posted recently. Both have a curl of stars on a spiral arm. Arp took the one in Arp 38 for a separate galaxy. Even though this one is very similar he didn't include it. Likely because this one is close enough to better resolve the curl and see it isn't a galaxy. Still shouldn't that have been a tip off that the curl in Arp 38 may be the same thing?

It is close enough that its brighter stars can be easily resolved by the Hubble Space Telescope. They have covered it in a press release. I'll save my fingers and let you read about the galaxy at http://www.spacetelescope.org/news/heic1202/ . For some reason the HII regions are left uncolored in the HST image rather than pink as they should be in a true color image. Apparently their image is not true color though it does seem to get the stars and bar reasonably correct.

The article points out three quasars seen right through the galaxy. NED shows a fourth even closer to the core. Problem is I think this might be an error. It is listed about the same brightness as the other three yet I can't find it in my image, the Sloan image nor the HST image which goes much fainter. I don't know if the press release missed it, skipped it because it is too faint for even their scope or it doesn't exist. The last seems most likely to me.

There are other quasars in the area. Most are just out of my field of view to the south. Most of the Sloan data at NED covers only the very bottom of my image but for the quasars. The other sources that do cover the rest of the image don't seem to have any redshift data for the galaxies, only the quasars. So the annotated image is a bit skimpy. Except for the two asteroids, one hard to find as it is nearly 21st magnitude, I probably wouldn't have prepared one. The "bright" 17.9 magnitude asteroid at the bottom right is (37563) 1988 SG2. The other at an estimated (by the Minor Planet Center) 20.8 magnitude is 2011 TY9. It has no number because it has yet to complete an orbit since its discovery last year. According to the Minor Planet Center the first observation of it was September 24.48 2011. My image was taken September 25.29 (start). Only one day later. It was observed by Pan-STARRS1 atop Haleakala on Maui. I almost beat them (well I didn't look at the frames until July, 2012).

14" LX200R @ f/10, L=4x10' RGB=2x10', STL-11000XM, Paramount ME


Ari Jokimaki
2012-Sep-21, 02:10 PM
The fourth QSO is quite clearly an error. NED refers to Arp et al. (2004) as the position reference to this fourth QSO, and the position data in NED is the same as in Arp et al. (2004). However, Arp et al. (2004) give the angular separation as 1.8’, which is the same as that of one of the three other QSO's ([HB89] 0240+011 NED02). Also redshift and magnitude of the fourth QSO in NED are exactly the same as in [HB89] 0240+011 NED02. Finally, the position data is otherwise the same but one number in right ascension differs. It seems that there is an error in the position data of Arp et al. (2004) for [HB89] 0240+011 NED02 which has caused the extra entry in NED.

By the way, SDSS DR9 has couple of additional redshifts in the field (click objects with spectra and increase width and height to see more objects, through navigate option you can get to details of individual objects):


There's a z = 0.187 galaxy (is that double-nucleus?) at about 11 o'clock looking from nucleus of NGC 1073:

At about 4 o'clock there's a z = 0.188 galaxy:

Further out there are others.

2012-Sep-22, 12:55 AM
Thanks, that's what I had decided was the best explanation.

NED hasn't included DR9 data yet so doesn't have these redshifts. I can pop those out fast in NED but never found a way to do it easily in with SDSS data. If you have a quick way of listing those in my field with this data it would help me a lot.


2012-Sep-29, 05:02 AM
That is wonderful! I really want to get a telescope, but I an downtown in a major city. I couldn't see a thing if I wanted to :(

2012-Sep-29, 05:51 PM
While deep sky observing isn't possible from downtown other fields certainly are. Planetary work either visual or photographic is just as easy from such a setting as dark skies. Double star work and variable star work can be done as well. Even with very bright skies you have a lifetime of targets for these subjects. Once experienced narrow band imaging of emission nebula is well suited for such skies. I lived in a major city only a couple blocks from its largest shopping area. Seeing only first magnitude stars but didn't let that slow me down. Just meant working very differently than I do now.

You might want to look at this website: http://www.slilge.de/ Most of his imaging is done from downtown Berlin. While he can't begin to go as deep as I can and needs all night to do what I can in 20 minutes it is still possible. Even when living in a major town I could pack up my gear and head to reasonably dark skies after an hour's drive. It's only since I've retired I moved to a dark sky site yet have been in the hobby since the early 1950's when I built my first telescope, a 6" reflector.

If you live in a major town you have an astronomy club. Google your town and astronomy club to find it. They will know all the tricks for your area.