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Gaia Science Alerts TEST at LOIANO 29-30 Jul 2011

Gaia Science Alerts TEST at LOIANO 29-30 Jul 2011 G. Altavilla - INAF Osservatorio Astronomico di Bologna. BFOSC@ 1.52m Cassini Telescope Field of View: 13'x12.6' Pixel scale: 0.58 arsec/pixel Lat. 44 15 33 N, Long. 11 20 02E, 785m asl UBVRI,Gunn

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Gaia Science Alerts TEST at LOIANO 29-30 Jul 2011

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  1. INAF-OABO, 29/09/2011 Gaia Science Alerts TEST at LOIANO 29-30 Jul 2011 G. Altavilla - INAF Osservatorio Astronomico di Bologna

  2. BFOSC@1.52m Cassini Telescope Field of View: 13'x12.6' Pixel scale: 0.58 arsec/pixel Lat. 44 15 33 N, Long. 11 20 02E, 785m asl UBVRI,Gunn V~22 in 30min, V~6-7 in 2-3 sec; (in spectroscopy V~18 in 30min, V~5-6 in 10sec) See here the comparison with other telescopes 1.5m, imaging ok, “wide” field useful for relative photometry

  3. CRTS Transient ID CSS110610:141829+354249 14 18 28.52 +35 42 49.4 mag~18 images bias & flat corrected, astrometry and phot. catalogues (SExtractor) everything on the fly, while observing (in two!) 151.fits > 110610_R.cat 2m 152.fits > 110610_B.cat 10m 153.fits > 110610_V.cat 5m 154.fits > 110610_Rbis.cat 5m 155.fits > 110610_Bbis.cat 10m 156.fits > 110610_Vbis.cat 5m 157.fits > 110610_R3.cat 5m http://nesssi.cacr.caltech.edu/catalina/20110610/1106101350644123477.html

  4. 110610, V 5min Ra/Dec or Long/Lat wcs rms: 0.193 0.149

  5. 110610 (B) (B) (R) (R) (R) (V) B matched to g V,R matched to r only zero point correction applied, no colour term (V) By Sergey Koposov

  6. 110610, Current CRTS lightcurve 2522

  7. CRTS Transient ID CSS110621:201624-090333 20 16 24.2 -09 03 33.2 mag~16 images bias & flat corrected, astrometry and phot. catalogues (SExtractor) everything on the fly, while observing (in two!) 564.fits > 110621_B 5m 565.fits > 110621_V 3m 566.fits> 110621_R 2m http://nesssi.cacr.caltech.edu/catalina/20110621/1106210091084179317.html

  8. 110621, V 3m Ra/Dec or Long/Lat wcs rms: 0.187 0.213 (arcsec arcsec)

  9. 110621 (V) (B) (R) B,V matched to USNO phot B R matched to USNO phot R only zero point correction applied, no colour term By Sergey Koposov

  10. 110621, Current CRTS lightcurve 2523

  11. Conclusions/comments Test successful Fast reaction (target selected in the afternoon, observed and analysed In the night) Big errorbars due to the cross-correlation with other photometric systems and to the missing colour term correction. First target: clear, airmass ~1.2, seeing ~1.5” Second targert: veils, airmass ~1.7, seeing ~2” Useful to compare the results under different sky conditions

  12. Target selection: “by hand”, in contact with Cambridge (L. Wyrzykowski, S. Koposv, and A. Mahabal from CRTS). Options: web page to be checked manually, skyalert, email, automatic system, iphone.... Data aquisition: no problem (at least for imaging and during the nights devoted to this programme, no real ToO) Data reduction: possible to measure the targets at the telescope while observing, provided that bias and flat images have already been acquired, but 2 observers are needed (especially if the observational programme is made up by short exposures). Since data products are expected by the following day, an observer can acquire the data to be reduced by other people the following morning (efficient transfer of data and calibration to be set up). Software used: Iraf (+wcstools+internet connection), SExtractor. Astrometric solution with an Iraf script of my own (can be adapted at other telescopes) very simple: in the best case the image name and the FWHM in pixel is enough. GSC2 reference catalogue. Sometimes an interactive shift of the solution may be necessary or, in the worst case, the coordinates of the center mut be specified manually in the parameters. The photometric catalogues produced by SExtractor (I used aperture magnitudes with 3 different radii), together with the images header must be sent to Cambridge by email... (better automated system? how? To whom? Skyalert portfolio?). Cambridge people calibrate the magnitudes by comparison with the catalogue mag of the fields stars. Hence Ra Dec and instrumental magnitudes are required, toghether with other info that can be retrieved from the images headers (JD for the light curve ecc..)

  13. By the way, both targets were blazars

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