UT Aug 17, 2023: Photometry of V347 Aur

Michael Richmond
Aug 18, 2023

On the night of Aug 16/17, 2023, under good conditions, I acquired images of V347 Aur as part of our optical monitoring program. All data was taken with the 12-inch telescope and ASI camera. The sky was mostly clear for these measurements, though some clouds interrupted for 20 minutes or so.

V347 is on the bright side this morning.

V347 Aur

V347 Aur is a young stellar object (YSO) which undergoes semi-periodic outbursts. I'm part of a team of astronomers who have applied for (and received) time on the XMM-Newton X-ray telescope to study this object in the fall of 2023. We have organized an observing campaign with the AAVSO to monitor the object in the optical in order to determine when the outburst begins -- if it begins! Our prediction is some time in mid-August, 2023.

These observations involved:

• Meade 12-inch telescope
• no focal reducer, so working at f/10
• ASI 6200MM CMOS camera
• B and V filters, 20-second exposures
• images binned 4x4
• no guiding
• focus position:
  • in V: 0.301 yields FWHM 2.6 at T = 66/19
  I shifted the focus up by +0.020 units for B-band later in the morning; the temperature was 64/18 at end of run.

Notes from the night:

• Opened after midnight. Very humid (around 95%) and warmish.
• no Moon
• a deer snorted on the lawn near the parking lot aroiund 4:30 AM
• when I arrived and logged into the computer in the dome, some of the icons had small "X" on them, and MaximDL did not remember its configuration. I think this is due to some failure to mount remote disks properly. The problem disappeared after 10-15 minutes, thank goodness. (This is similar to behavior I've seen in the recent past, on some nights)

The position of the variable star is

   RA =  04:56:57.02   Dec = +51:30:50.9

At quiesence, it has magnitude V = 16-ish, but can rise to V = 12 in an outburst.

• chart of V347 Aur field from AAVSO

Here's a chart from the DSS2 Red plates, 0.6 degrees on a side.

The picture below, based on a stack of images taken on UT Jul 23, 2023, shows the area in the red box above. The variable is at its quiescent level in this image.

I've marked the location of several comparison stars.

  star       AAVSO ID            B          V         
------------------------------------------------------
   B            140              15.134    14.001                           

   C            127              13.617    12.660

   D            154              17.491    15.361
--------------------------------------------------------------------------

 

Here's a picture of the guider TV when pointed at the field (pointed slightly to the left of the variable, actually).

Tonight's stacks were formed from 57 x 20 sec for V-band and 52 x 20 sec, then 74 x 20 sec for B-band (with a brief interruption due to clouds between the two B images). In the B-band median images, I could barely detect star "D", used for calibration.

I reported the following to AAVSO:

    JD             filter          mag
---------------------------------------------------
  2460173.85        B         16.1  +/- 0.3 
  2460173.88        B         16.2  +/- 0.3 

  2460173.83        V         14.89 +/- 0.11

---------------------------------------------------

The variable is about the same it was a few nights ago. However, my colleague Bart Staels has informed me that the system has brightened more recently -- good!