V-Band Photometry of IGR J06074+2205
ATel #16560; P. C. Schmidtke (Arizona State University), T. B. Hunter (Grasslands Observatory), A. P. Cowley (Arizona State University)
on 30 Mar 2024; 18:59 UT
Credential Certification: Paul Schmidtke (Paul.Schmidtke@asu.edu)
Subjects: Optical, X-ray, Binary, Neutron Star, Pulsar
The X-ray source IGR J06074+2205 was discovered with INTEGRAL during an X-ray outburst on 2003 February 15-16 (Chenevez, ATel #223). The proposed optical identification with a Be star (Halpern, ATel #682) was confirmed using an improved X-ray position from Chandra (Tomsick, ATel #959). X-ray pulsations with P=374 s were found by Malacaria (ATel #16307) and Nakajima (ATel #16401). Hence, the source is a Be/X-ray binary.
After a long X-ray quiescence, additional outbursts were detected on 2022 March 23 (Nakajima, ATel #
15294) and 2023 October 3 (Semena, ATel #
16267). Combining the dates of prominent outbursts with the date (2022 June 10) of a weaker one found in archival data, Mihara (ATel #
16351) proposed an 80 +/- 2 d orbital period and predicted an X-ray outburst for 2023 December 28. Nakajima (ATel #
16394) reported an outburst occurred 2023 December 26 (within the +/- 2 d window), confirming the prediction. The next outburst was expected on 2024 March 15. A single observation taken with Swift-XRT on 2024 March 12 shows a count rate consistent with the onset of another outburst (Nesci, ATel #
16525).
We monitored the optical counterpart of IGR J06074+2205, obtaining 26 V-band observations on 9 nights between 2023 December 3 and 2024 March 17. The images were taken with a Proline KAF-09000 CCD camera on the 0.6-m telescope at Grasslands Observatory and calibrated using observations of Landolt photometric standards in Selected Area 95. The results are shown in the table below. The star slowly faded by ~0.07 mag over the 105-d interval, but no significant short-term brightening was observed. The V data taken on 2023 December 31 came ~5 days after the detection of an X-ray outburst, hence an optical brightening might have been missed. In contrast the V observations from 2024 March bracket the time when an X-ray outburst was in progress. The optical brightness, however, remained relatively steady, with a possible brightening of ~0.01 mag on the last night. If present, an optical outburst would have to be of very short duration to be undetected. Additional observations in BVR are in progress.
Date [UT] | V Magnitude
2023-12-03.2100 | 12.327 +/- 0.0096
2023-12-03.2105 | 12.327 +/- 0.0090
2023-12-03.2111 | 12.319 +/- 0.0128
2023-12-03.2290 | 12.308 +/- 0.0408
2023-12-03.2299 | 12.310 +/- 0.0285
2023-12-03.2309 | 12.313 +/- 0.0153
2023-12-09.1866 | 12.321 +/- 0.0111
2023-12-09.1873 | 12.326 +/- 0.0201
2023-12-09.1881 | 12.322 +/- 0.0250
2023-12-31.1447 | 12.333 +/- 0.0094
2023-12-31.1454 | 12.326 +/- 0.0091
2023-12-31.1462 | 12.322 +/- 0.0077
2024-02-04.1719 | 12.354 +/- 0.0228
2024-02-04.1727 | 12.365 +/- 0.0126
2024-02-04.2215 | 12.374 +/- 0.0186
2024-02-04.2223 | 12.360 +/- 0.0130
2024-03-01.1689 | 12.382 +/- 0.0157
2024-03-11.1483 | 12.381 +/- 0.0212
2024-03-11.1491 | 12.383 +/- 0.0133
2024-03-12.1788 | 12.397 +/- 0.0098
2024-03-12.1795 | 12.394 +/- 0.0091
2024-03-13.1485 | 12.379 +/- 0.0092
2024-03-13.1492 | 12.376 +/- 0.0071
2024-03-17.1887 | 12.370 +/- 0.0261
2024-03-17.1895 | 12.365 +/- 0.0381
2024-03-17.1902 | 12.365 +/- 0.0189
