sigma Gem campaign - Alert Notice 837

Affiliation
American Association of Variable Star Observers (AAVSO)
Wed, 10/18/2023 - 17:50

Alert Notice 837 announces an observing campaign on the bright RS CVn variable sigma (sig) Gem. For details and observing instructions (campaign is best suited to PEP but CCD/CMOS may be possible), please see the notice.

There is a thread for this campaign under the following AAVSO forum:

 - Campaigns and Observing Reports: https://www.aavso.org/sigma-gem-campaign
 

Please subscribe to this thread if you are participating in the campaign so you can be updated, ask questions, and join in the discussion!

Many thanks, and Good observing,

Elizabeth O. Waagen, AAVSO HQ

Affiliation
American Association of Variable Star Observers (AAVSO)
I band magnitudes

Ben Taylor's 1986 paper, TRANSFORMATION EQUATIONS AND OTHER AIDS FOR VRI PHOTOMETRY, ApJS, provides R-I for both the comparison and check stars.

Comp HD58207/HR2821   R-I = 0.471

Check HD60522/HR2905   R-I = 0.850

 

Using the VSP Rc magnitudes yields comparison I = 2.796

                                                                     check I = 2.337

 

Taylor also provides V-R for the check star as 0.860.  This is reasonably close to the VSP value of 0.873, which has a very large uncertainty.

Affiliation
American Association of Variable Star Observers (AAVSO)
HD 61911

A note to CCD observers (e.g. the AAVSOnet BSM systems), the nearby red star HD 61911 is a tempting comparison but I will note that it shows variability at the ~1% level in previous TESS data. Since TESS will observe it simultaneously with sigma Gem, it might be possible to correct for its variability but I wanted to make people aware of it. HD 63138, about a degree to the east, looks much more stable if you can get it in your FoV.

Affiliation
American Association of Variable Star Observers (AAVSO)
000-BPS-000

CCD observers have been using 000-BPS-000 (HD 61911) as a comparison.  The Variable Star Plotter has a new message about this star: "HD 61911 - SRS+ORG - V= 7.70 - 7.74. ONLY FOR VISUAL USE."

 

This is presumably due to the VSD cleanup.

Tom

Affiliation
American Association of Variable Star Observers (AAVSO)
Campaign status

Thanks for asking, Ken. I asked Shashank about the status of the campaign earlier this week and expect to hear from him shortly. He or I will post here as soon as possible.

Good observing,

Elizabeth