Skip to main content

Alert Notice 703: TCP J21040470+4631129 images, photometry, and spectroscopy urgently requested - REVISED

Note: This Alert Notice was revised from its original text to correct a misinterpretation of the request from Dr. Echevarria, to update the recent observations, and to update the status of scheduled HST observations.  -  Elizabeth O. Waagen, 2 April 2020

April 2, 2020   (original issued April 1, 2020)

AAVSO Forum threads (scroll to the bottom of a thread for latest posts):
- Campaigns and Observation Reports:
- Cataclysmic Variables:
- Spectroscopy:

Dr. Juan Echevarria (Instituto de Astronomia, UNAM) has requested AAVSO observers' assistance in acquiring images and carrying out spectroscopy and photometry of the WZ Sge cataclysmic variable TCP J21040470+4631129, which is undergoing a superoutburst.

Dr. Echevarria asks CCD photometrists for images "taken with a narrow filter, centered at H alpha and also in nearby continuum."

Photometry in V is also requested, as most large ground-based telescopes are closed at present. High speed photometry is requested to analyze superhump behavior. TCP J21040470+4631129 is a morning object, but knowing the magnitude is crucial so photometry is essential.

Spectroscopy focused on H alpha is also encouraged.

Please continue images, photometry, and spectroscopy of TCP J21040470+4631129 at least through the end of April 2020.

This Alert Notice is complementary to the request for photometry by Dr. Boris Gaensicke in AAVSO Alert Notice 702. Observers are reminded that knowing the V magnitude of TCP J21040470+4631129 is essential to that campaign. Dr. Echevarria asked that this message from Dr. Gaensicke be included here: "HST/COS far-ultraviolet spectroscopy of [TCP J21040470+4631129] are scheduled for April 10, 2020 17:15:48 - 23:05:48 UT. The COS far-ultraviolet detector has a limited dynamical range, and over-illumination risks permanent damage. Therefore, the standard procedure to observe highly variable sources is to have daily monitoring in place to ensure that the target remains quiescent in the 24h prior to the HST observations. Given that TCP has just entered an outburst, it is now mission-critical to closely monitor the flux level over the next ten days, so that STScI can gauge whether it is safe to observe TCP. Given the way HST operates, the schedule cannot be altered at this point, and should TCP remain too bright, or the monitoring be insufficiently dense, HST will observe a blank piece of sky instead, resulting in the loss of four space-craft orbits.”

Note added in revision: The HST observations have been postponed to a later date. Please monitor the forum threads given in AAVSO Alert Notice 702 for updates on the HST re-scheduling.

TCP J21040470+4631129 has a range in V of 8.4-18.1. The most recent observations submitted to the AAVSO International Database include:

2020 Mar. 28.18190 UT, 15.170 V +/-0.024 (S. Dufoer, Brussels, Belgium);
28.18318, 15.173 V +/-0.084 (Dufoer);
30.15139, 15.4 CV (K. Wenzel, Grossostheim, Germany);
30.16976, 15.144 V +/-0.017 (F. Dubois, Zillebeke, Belgium);
30.17125, 15.491 B +/-0.019 (Dubois);
30.17275, 14.758 R +/-0.022 (Dubois);
30.17426, 14.346 I +/-0.046 (Dubois);
31.47796, 11.115 CV +/-0.004  (D. Denisenko, Moscow, Russian Fed.);
Apr. 01.01507, 10.638 B +/-0.020 (D. Boyd, Wantage, Oxon, UK);
01.01558, 10.774 I +/-0.022 (Boyd);
01.01598, 10.799 R +/-0.027 (Boyd);
01.01627, 10.826 V +/-0.018 (Boyd);
01.04087, 10.813 V +/-0.004 (T. Tordai, Budapest, Hungary);
01.05056, 10.805 V +/-0.004 (Tordai);
01.054, 10.6 TG (R. Fidrich, Budapest, Hungary);
01.10284, 10.845 V +/-0.003 (Tordai);
01.18491, 10.751 V +/-0.084 (T. Vanmunster, Landen, Belgium);
01.21547, 10.746 V +/-0.085 (Vanmunster);
01.81814, 10.870 V +/-0.005 (A. Oksanen; Muurame, Finland);
01.86287, 10.858 V +/-0.005 (Oksanen);
01.94559, 10.905 V +/-0.005 (Oksanen);
02.03445, 10.876 V +/-0.007 (Oksanen);
02.12200, 10.8 (W. Vollmann, Vienna, Austria);
02.37014, 10.9 (L. Shotter, Uniontown, PA);
02.42070, 11.022 V +/-0.005 (B. Harris, New Smyrna Beach, FL);
02.42156, 10.904 B +/-0.007 (Harris);

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 submit CCD images to Dr. Echevarria at <>.

Please submit spectroscopy reports to Dr. Echevarria at <> and to the AAVSO Spectroscopy Database (AVSpec).

Please submit photometry observations to the AAVSO International Database using the name TCP J21040470+4631129.

This Alert Notice was compiled by Elizabeth O. Waagen.

Information on submitting observations to the AAVSO may be found at:


An Alert Notice archive is available at the following URL:

Subscribing and Unsubscribing may be done at the following URL:


Please support the AAVSO and its mission -- Join or donate today:



AAVSO 49 Bay State Rd. Cambridge, MA 02138 617-354-0484