Note: The HST observations of AB Aur scheduled for 2024 January 17-18 have been cancelled because HST has gone into safe mode. Rescheduling information will be given here and in the forum threads below when available. In the meantime, please continue to observe AB Aur according to the cadence given below. - Elizabeth O. Waagen, January 17, 2024
January 15, 2024
AAVSO Forum threads (scroll to the bottom of a thread for latest posts):
- Campaigns & Observation Reports: https://www.aavso.org/ab-aur-campaign-2023
- Young Stellar Objects: https://www.aavso.org/ab-aur-campaign-2023-01
Please subscribe to these threads if you are observing this star so you can be updated by the astronomers and by HQ. Join in the discussion or ask questions there!
Further to AAVSO Alert Notice 842 (and Alert Notices 809, 811, 814, 844), Dr. Lauren Biddle (University of Texas) informs us that observations of the the bright (6.9-8.4V) young, accreting A0 Herbig Ae star, AB Aur, have been scheduled with the Hubble Space Telescope on:
17-18 January 2024 as follows (Universal Time):
17 Jan 09:08:41 - 10:08:08
17 Jan 20:13:06 - 21:12:33
17 Jan 21:48:01 - 22:47:28
17 Jan 23:22:56 - 18 Jan 00:22:23
Observers are asked to focus especially on January 15 - 19 UT (and continue coverage now through February).
There has been considerable discussion about this campaign in the forum threads above. Observers are urged to read these posts (scroll to the end of the thread to see the most recent posts). Observers are also reminded of the very interesting webinar on AB Aur and this campaign that took place on November 19, 2023. View the video on the AAVSO's YouTube channel here: https://www.youtube.com/watch?v=yPrW99Icrg8
The following instructions are repeated from Alert Notice 842:
Filters:
CCD or photoelectric (PEP) photometry is requested. Rc is preferred, then B and V. Unfiltered photometry (CV or CR) and DSLR observations are acceptable but will receive lower priority in the final analysis than filtered CCD/PEP observations. CCD observers are reminded to be very careful not to saturate their exposures of this bright target.
Observers with Halpha filters are asked to prioritize this filter over all others, as observations made with it will best support the science goals of the campaign. Please use the Rc magnitude of the comp star for your Ha photometry reference and report to the AAVSO database as an Ha magnitude. Please read the discussion in the forums above regarding Ha observations.
Comparison Stars:
All observers are requested to use GSC 02387-00489 (the 104 in the AAVSO AB Aur sequence, Rc = 10.071) as their single comp star and GSC 2387-0935 (the 120 in the sequence, Rc = 11.382 [this is the correct magnitude]) as their check star. Single comp star photometry is strongly preferred for this campaign.
Cadence:
Dr. Biddle writes: "The science goals of this campaign would be best supported by a time-series with observational cadence that covers a range of timescales: medium-cadence (daily), and low-cadence (weekly and monthly). An ideal observing plan that satisfies the desired cadences would look something like: 3 – 5 observations over the course of the night, with each night separated by a few days to a week, repeated throughout the months of November 2023 through February 2024."
Because the comp and check stars for this campaign are 3 and 5 magnitudes fainter than AB Aur, observers are asked to take multiple exposures in each filter and stack the exposures to attain a comp star S/N of 100 or more while not overexposing AB Aur.
There has been considerable discussion about this campaign in the forum threads above. Observers are urged to read these posts (scroll to the end of the thread to see the most recent posts).
Observers are reminded of the very interesting webinar on AB Aur and this campaign that took place on November 19, 2023. View the video on the AAVSO's YouTube channel here: https://www.youtube.com/watch?v=yPrW99Icrg8
Coordinates (2000.0): R.A. 04 55 45.84 Dec. +30 33 04.3 (from VSX page for AB Aur)
Charts with comparison stars for AB Aur may be created using the AAVSO Variable Star Plotter (VSP). It is recommended that observers use the 'E' scale when creating charts for AB Aur. Be sure to create new charts for this campaign - do not use ones you may have from earlier observing, as there have been changes to the comparison stars. Observers should be aware that the 116 comp star appeared in earlier versions of the AB Aur sequence, but is not the recommended comp star to use for these observations.
Please submit observations to the AAVSO International Database using the name AB AUR.
This AAVSO Alert Notice was compiled by Elizabeth O. Waagen using information provided by Lauren Biddle and Walt Cooney.
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SUBMIT OBSERVATIONS TO THE AAVSO
Information on submitting observations to the AAVSO may be found at:
- Photometry/visual observations: https://www.aavso.org/webobs
- Spectroscopy: https://www.aavso.org/apps/avspec/
ALERT NOTICE ARCHIVE AND SUBSCRIPTION INFORMATION
An Alert Notice archive is available at the following URL:
https://www.aavso.org/aavso-alert-notices-for-observing-campaigns-and-discoveries
Subscribing and Unsubscribing may be done at the following URL:
https://www.aavso.org/aavso-alert-notice-subscribe
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