Alert Notice 714: TCP J21040470+4631129 to be observed with HST

Note: Additional HST observations may be scheduled, so please continue obtaining 2-3 V snapshots per week. When a decision is made about any further HST observations (and consequent cadence changes), that information will be communicated via the forum threads for this campaign. Please be sure to subscribe to stay informed! - Elizabeth O. Waagen, 1 October 2020

Note: The HST observations of TCP-J21040470+4631129 have been scheduled for

Sep 12, 2020 07:16:37 to 13:07:28 UT

For the HST observations to take place, it is essential to have a positive observation 24 hours before this time showing the system in quiescence, so the night of September 10-11 UT is crucial.  -  Elizabeth O. Waagen, 31 August 2020

August 6, 2020

AAVSO Forum threads (scroll to the bottom of a thread for latest posts):
- Campaigns and Observation Reports: https://www.aavso.org/tcp-j210404704631129-hst-campaign
- Cataclysmic Variables: https://www.aavso.org/tcp-j210404704631129-hst-campaign-01
Please subscribe to these threads if you are participating in the campaign so you can be updated by the astronomers and by HQ. Join in the discussion or ask questions there!

(Note: This campaign was originally scheduled for March and April but was postponed due to the outburst of the system in March 2020.)

Dr. Boris Gaensicke (University of Warwick) has requested AAVSO assistance in monitoring the WZ Sge-type dwarf nova TCP J21040470+4631129 (Cygnus) in support of observations scheduled with the Hubble Space Telecope for Sep 12, 2020 07:16:37 to 13:07:28 UT sometime between 2020 September 8 and 20.

All dates in this Alert Notice will be refined when the exact date/time of the HST observations is released by STScI. It is extremely important for observers to subscribe to the forum threads given above for the campaign so as to be informed of the exact date and time of the HST observations. This Alert Notice will also be updated with the exact date and time.

AAVSO observations are essential to know the state of TCP J21040470+4631129 in order to ensure that the system is NOT in outburst when observed with HST. AAVSO observations made 24 hours before the HST observing time will be used to make a go/no-go decision; AAVSO data will be used in the analysis of the resulting HST data.

Nightly snapshots in V are requested beginning now and continuing through September 15 September 25 (date may change). Intensive monitoring is requested September 9 - 12 September 6 - 20 (dates will change). During the period of intensive observations, prompt submission of observations will be essential. The most critical need for a positive observation is the night that is 24 hours before the HST observations (September 10-11) (to be announced). Visual observations are also welcome.

TCP J21040470+4631129 has a range in V of 8.4-18.1. Its last major outburst occurred in July 2019, when it reached magnitude 8.293 V, and was followed by several re-brightenings, the most recent of which occurred in March 2020. The most recent observation of TCP J21040470+4631129 in the AAVSO International Database shows it at magnitude 15.248 V +/-0.083 on 2020 Aug. 05.0108 UT (S. Dufoer, Brussels, Belgium).

Coordinates (J2000): R.A. 21 04 04.68  Dec. +46 31 14.5

Charts with comparison stars for TCP J21040470+4631129 may be created using the AAVSO Variable Star Plotter (VSP).

Please report all observations to the AAVSO International Database using the name TCP J21040470+4631129.