(Almost) new Mira

[Rob_K]

Took the camera out last night despite the nearly full Moon to continue a long-interrupted nova search. Vela & Carina were well-placed so I took 55mm shots over those areas. Pretty ordinary washed-out subs but I blinked them against earlier shots anyway - very different exposures so I was only looking for very bright stuff. With the very last section blinked on the second stack I noticed a reddish star that blinked on & off. Did all the usual searches (DSS plates, AAVSO VSX, MPChecker etc) but zilch. Then checked each sub and it appeared to be in three but nothing in the fourth. What??? Took the gear out again and imaged tighter at 200mm but zilch. Rats! :mad2:

Anyway, I had a 'nice' shot of the Southern Pleiades and on the spur of the moment decided to blink it against a shot taken in March 2012 for Nova Carinae 2012. Yep, the nova was blinking on and off nicely, but there was another star also blinking on and off! Damn! Did all the searches & checks again. On the DSS plate there was a star at that position (listed in the 2MASS catalogue), but at almost mag 16 it was several magnitudes dimmer. No variable star was listed at that position in AAVSO's variable star catalogue (VSX). So I reported it on vsnet_alert.

http://i727.photobucket.com/albums/ww271/Rob_Kau/2MASSJ10411620-634548726Dec2012.jpg

Turns out the star had been spectroscopically identified as a Mira in Jack MacConnell's southern far-red spectral survey from plates taken on 18 Apr 1972. But that was the only observation of it. The ASAS-3 survey which covers countless southern stars has it hidden in its data, but unrecognised. It is one of those bright Mira-type stars that has gone unnoticed. I've been told I can submit it to VSX using ASAS as reference.

Here's the ASAS light curve - this was posted on vsnet_alert, I have problems accessing ASAS data, don't know if it's a browser & settings prob. :shrug:
http://www.astrouw.edu.pl/cgi-asas/asas_variable/104116-6345.8,asas3,423,4175,460,260,0

So no nova, not quite a new variable star discovery, but an excellent night anyway! :D

Cheers -

[PeterM]

:thumbsup:Great work anyways! There is much skill and effort in what you have done.
Peter

[Merlin66]

Rob,
congratulations on a job well done!
I'm impressed with your diligence and rigor....
Unfortunately too many amateurs just take " pretty pictures" and never have the discipline to check their images for any new discoveries....what a waste of collected photons......

[Rob_K]

Thanks Peter & Ken - haven't really done much since October with a killer work-holiday-work combo curtailing astronomy (er, except for the eclipse)! Gotta get ASAS working - can access the search page but can't bring up search results.



And you don't really need much gear to contribute. Don't think that you need expensive CCD cameras, top quality mounts & scopes, sophisticated software etc, as well as a massive learning curve.

It can be as simple as you want it to be. My own philosophy has always been that I have certain gear, so what can I do with it? Rather than saying, I'd like to do such-and-such so what hardware/software do I need to buy to do it?

I just have a battered 400D, cheap zoom lens and an unmotorised EQ1 mount that is badly worn out & sloppy. To blink I just layer one image over another in Photoshop or PS Elements and flip the layer transparency from 0 to 100%, backwards & forwards. No special software. Piggybacked shots at 55mm are quite sufficient for a nova search and even if you don't discover one (I've been oh so close a couple of times over the last few years but no cigar... yet!), you can provide confirmation (or otherwise) for new possible novae, or heads-ups for unusual novae or vs behaviour, or maybe even discover a variable star or two! Especially for southern stars which tend to be under-observed.

This is apart from the fascination of seeing the galaxy in action (stars dim, others brighten) and the learning experience as you chase down the story behind little changing dots in your images.

Cheers -

[avandonk]

Good stuff Rob.

I do not know what to do with this. Your post reminded me.

http://d1355990.i49.quadrahosting.com.au/2013_01/pmotion.gif

I was comparing a DSS image to one of mine when I noticed what looks like large proper motion of one of the stars just to the left of Thors Helmet. I was really trying to see the PN, see the bottom images.


Bert

[Rob_K]

Well spotted Bert! :thumbsup: With a quick search it seems to be PPMX 071735.3-122736 in the the PPMX Catalog (Position and Proper Motions Extended), with a proper motion in RA of 55.25mas/yr and in DEC of -324.17mas/yr (info from VizieR).
http://vizier.u-strasbg.fr/viz-bin/VizieR-5?-info=XML&-out.add=.&-source=I/312/sample&PPMX===071735.3-122736

The movement shown in your image is a small fraction of an arcminute but the DSS Colored plates would still have to be reasonably old - can't find a date for them. :shrug:

Cheers -