Affiliation
American Association of Variable Star Observers (AAVSO)
Fri, 02/09/2018 - 15:20
New transient object in M-31 (quite near NGC 221/M32): http://www.astronomerstelegram.org/?read=11275
I've imaged this, and uploaded BVR images to VPhot, but there are very few comp stars in the field. Would like to know if there are other standard or comp stars that I could access?
Clear skies,
Brad Vietje, VBPA
Newbury, VT
I sent in a sequence request and Tim Crawford Jumped all over it -- Thank you for such light-speed work!!!
Lots of comps now : )
~Brad
We just submitted ASASSN-18ca to VSX and requested an AUID. Once the submission has been reviewed and approved, it should appear in VSX with an AUID. After that time observers will be able to generate AAVSO charts for this probable nova. We will be issuing an Alert Notice.
Good observing,
Elizabeth Waagen, AAVSO HQ
Brad
Thanks, Elizabeth!
Brad
It is always fun to image a transient object in another galaxy. As M31 is nearby, beautiful to image, and similar to our own galaxy, there are several groups that monitor it nightly for transient events. At that distance, a typical nova peaks at about 16th magnitude, and so doable with most amateur telescopes.
A couple of words of warning. M31 is near the plane of the Milky Way, and so you are looking through the cloud of MW stars towards the galaxy (one of the reasons of its beauty!) In addition, M31 is overexposed on the POSS plates that make up the Digital Sky Survey (DSS) option for the Variable Star Plotter (VSP). So fainter stars are not always obvious on those charts. Luckily, SDSS covered this area, so I've attached an Aladin-lite 2arcmin finder chart. The bright star to the north is about 14arcsec distant, and unlikely to bother most observers. However, there are two fainter stars to the NNW that will likely be in your photometric apertures, and so the magnitude of the nova as it fades will likely be brighter than reality. The field looks blank on VSP, but at 19-20mag, there are lots of M31 stars beneath the nova (which is why the background in this finder chart looks noisy)!
The comp stars are from APASS, which only goes down to V=16 or so. For CCD observers, it is ok to use comps that are brighter than the target as the sensor is linear. Just make sure that they do not saturate.
Enjoy!
Arne
AAVSO Alert Notice 615 reports on the probable nova in M31, ASASSN-18ca = PNV J00423439+4044255. Please see the notice for details and observing instructions.
Many thanks, and Good observing,
Elizabeth Waagen, AAVSO HQ
Hi Elizabeth,
I see that VSX now lists this object (AUID = 000-BMP-128), a.k.a. PNV J00423439+4044255. I can print out a finder chart and generate a photometry table.
However, WebObs will not allow me to upload observations (AAVSO reports generated by MaxIm DL 6.13).
In case anyone is trying to follow the evolution of this target, I'll attach my measures here, (B, V, & R, though sadly, no I), though adding them to the database would still be ideal.
Clear skies,
Brad Vietje, VBPA
Newbury, VT
www.nkaf.org
Well -- some success.
I went into the reports and added the hyphen, which worked for the B & V reports, but WebObs still won't take the R data. Hmmm.... curiouser and curiouser.
Clear skies,
Brad Vietje, VBPA
I did a 1200s B filter image with a 12.5" RCOS, and found no trace of the nova, the circles are around the position shown in the finder chart, but nothing is there. 600 second R and V, also no sign of the nova
No clue how this happened, but my VPhot-generated AAVSO report had an additional "R" after the target name, so it would not load in WebObs till I discovered the error and edited the report. I don't remember doing anything different, but the original report (attached, above) would not load until fixed.
Couldn't get on this target earlier tonight, before it was too low -- will try again when skies allow.
Clear skies,
Brad Vietje, VBPA
Newbury, VT
www.nkaf.org