SIMBAD references

The Be/X-ray binary pulsar A 0535+262 is currently undergoing a giant outburst (ATel #3166, #3173, #3176). We observed A 0535+262 in the radio band at 4.9 GHz with WSRT on 2011 February 23 (15:50-20:50 UT), three days after the periastron passage, when the 2-20 keV MAXI/GSC flux was 0.63 Crab and the 15-50 keV Swift/BAT flux was approximately 3 Crab. We did not detect the source at the optical position listed in the USNO-B1.0 catalog (RA (J2000): 05h38m54.574s; Dec (J2000): +26d18'56".82) to a 3 sigma upper limit of 0.16 mJy/beam. A non-detection was also reported by Tudose et al. (2010; ATel #2798) during the previous source activity. This is the most constraining radio upper limit on A 0535+262 to date.