TITLE:   GCN CIRCULAR
NUMBER:  37014
SUBJECT: EP240801a: Leavitt Observatory optical observations
DATE:    24/08/02 13:20:21 GMT
FROM:    leavittob@gmail.com

L. Moretti  and E. Pavoni (Leavitt Observatory, Italy), in a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan),
Y. Niino (Tokyo University, Institute of Astronomy),
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Universita' degli Studi Di Salerno)
report:

We imaged the field of the X-ray transient EP240801a detected by Einstein Probe (EP, Zhou et al., GCN 36997; Fu et al., GCN 36998; Li et. al. GCN 36999; Zheng et al, GCN 37000; Aryan et al. GCN 37002; An et al., GCN 37004; Pérez-Fournon et al., GCN 37007; Malesani et al., GCN 37008; Zhu et al., GCN 37010; Moskvitin et al., GCN 37012), with the telescope of Leavitt Observatory, Italy. Member of:

UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili, GRB section.
ATA - Associazione Tuscolana di Astronomia.

The transient event started at 2024-08-01 09:06:03 (UTC).
Our observations started about 11 hours after the EP trigger, with a RC telescope D=250 mm F/D=8.
Weather conditions were good.

We co-added 12 images of 120 sec each. All images are unfiltered, calibrated with masterdark and masterflat.

An uncatalogued optical transient (OT) is marginally detected in the stacked image at coordinates:
R.A. (J2000) = 23:00:39.02
Dec. (J2000) = +32:35:37.2

with the following photometry: 

Date UT Middle: 2024-08-01 20:48:27 UTC
CR-mag 21.4 +/- 0.2

Given the low S/N for the OT, we cannot completely rule out it being due to background fluctuation. 

Magnitudes were estimated with the Pan-STARRS cat. and converted using Lupton (2005) equations. No corrected for galactic dust extinction.


Reference:
https://leavittobservatory.altervista.org

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