AAVSO Alert Notice 800 announces a campaign beginning immediately on 5 YSO stars in Taurus and Orion. Please see the notice for details and instructions.
There are threads for this campaign under the following AAVSO forums:
Please subscribe to these threads if you are participating in the campaign so you can be updated. Join in the discussion or ask questions there!
Many thanks, and Good observing,
Elizabeth O. Waagen, AAVSO HQ
I would like to ensure my observations are concurrent with your spectroscopic observations. Are these dates UT? Is is possible to provide timing in UT for each specific YSO? Or perhaps anything more specific that would assist us in providing concurrent photometric observations?
Yes these dates are UT as stated in the notice. Unfortunately we can not provide timing because at the observatory they'll observe when they can. However, observations on the same night will still be highly valuable.
Thank you Mr. Kahar for updating the alert text and clarifying your request for observations. I now understand that observations taken after sunrise has occurred at Caro Alto will be of benefit to your study.
I am puzzled: usually a star is disc-shaped, but R Mon is sort of fan-shaped. How should I make photometric measurements of such a star? Shall I enlarge the aperture until all the "fan" is included, or should I restrict the aperture to what I believe to be the actual star (the disc at the end of the "fan") and exclude the rest by enlarging the gap?
You should restrict the aperture to the actual star, so in this case the bottom of the fan shape. For R Mon it would be useful for us to also get the images just in case they need to be recalibrated since it is a very complex system.
Of course, a…
Of course, a little bit of the "fan" (which I will try to keep as small as possible) will be included in the aperture...
Unfortunately, at present I have only one series (the weather has been quite bad), but I have the images, if you want them (just tell me where to send them).
Images uploaded. Unfortunately, I have forgotten to erase some non-FITS files in the subfolders before uploading (reports, screenshots etc). I have tried to erase them from OneDrive, but I am not permitted to do so. Apologies.
I was able to collect data on CO Ori for seven hours between 2022/11/27/0600 UT and 2022/11/27/1300UT in V, B, Rc bandpass. Unfortunately I do not have an I filter.
Would you like this data? If so, I can upload to you. Would you prefer raw uncalibrated data or calibrated?
We would appreciate having the calibrated data for CO Ori. Any filter you were able to take data in will be useful for comparisons to the spectroscopy.
I have uploaded the CO Ori data in folders: 11272022_V_Cal_Combined_CO ORI, 11272022_B_Cal_Combined_CO ORI, and 11272022_Rc_Cal_Combined_CO ORI.
All data are instrumental magnitude. The gaps in each set of data are due to transit/meridian pauses. The 'combined' word in the folder name indicates pre-transit and post-transit data have been combined into one folder. Please confirm receipt of all three folders, one upload gave me an error message. I am hopeful this will be of assistance to your research.
I would suggest adopting some measuring aperture that's as small as is reasonable for your telescope image-scale, such that you can always use that aperture consistently, even if conditions vary. Another ploy is to use exposures somewhat shorter than you might otherwise given the star's brightness, but take averages of 5 or 10 images at each visit.
FWIW, the ASAS-3 lightcurve shows the complete star+nebula to be hardly variable over several seasons.
Thank you, Brian.
Yes, I have indeed used the smallest reasonable aperture for the images. I have not stacked the images, whose exposures are 25, 10, 10 and 15 seconds in the filters BVRI. It would indeed have been possible to use shorter exposures and stack the images, but I din not do so. Unfortunately, the campaign ends tonight, and the weather has not been good in this period of the year (including tonight).