Pre-outburst detections of Nova Delphini 2013 from iPTF
ATel #5308; S. Tang (Caltech/UCSB), E. O. Ofek (Weizmann), M. M. Kasliwal (Carnegie/Princeton), L. Bildsten (UCSB), S. R. Kulkarni (Caltech), and B. Sesar (Caltech) on behalf of the iPTF collaboration
on 21 Aug 2013; 21:13 UT
Credential Certification: Sumin Tang (firstname.lastname@example.org)
Subjects: Optical, Nova, Star, Transient
We report pre-outburst detections of Nova Delphini 2013 (CBET #3628) from the intermediate Palomar Transient Factory (iPTF; ATel#4807). We are undertaking a Halpha narrow band survey during bright time at the Palomar 48inch telescope. Two narrow band (about 7nm) filters are used in the survey, with central wavelengths of 656nm and 663nm, respectively. Each exposure is 60s, and the limiting magnitude is about 18 (AB).
There were three pairs of narrow-band images taken with Halpha656nm and 663nm filters on UT April 28, 2013. Nova Delphini 2013 was detected in all images. Here are the AB magnitudes:
date Halpha-656nm 663nm
2013-04-28.39 17.1+/-0.1 17.0+/-0.1
2013-04-28.43 16.8+/-0.1 16.8+/-0.1
2013-04-28.47 16.7+/-0.05 16.5+/-0.14
We note that there is still a 0.2 mag uncertainty in the magnitude calibration. Therefore, there is no strong indication of Halpha emission in these images. These magnitudes are consistent with the other pre-outburst measurements in R band: R=17.6 in GSC2.2 (year 1990.7), and r'=16.8 in the Carlsberg Meridian Catalog 14 (during 1999-2005).