Variable stars near β Cas discovered on scanned photographic plates at the Sternberg Astronomical Institute Alexandra M. Zubareva, Daria M. Kolesnikova, Kirill V. Sokolovsky, Sergei V. Antipin, Nikolai N. Samus IX Bulgarian – Serbian Astronomical Conference: Astroinformatics Sofia, 2–4 July, 2014

Moscow collection of astronomical plates D, cm F, cmField, degrees m lim yearsNSite ×2813–141895– Moscow, S × – Moscow, T ×61955– Moscow … × – Moscow ×1017–181948– Kuchino, Crimea, A ×3.518–191958– Crimea 50200Spectra1959– Crimea ×0.613–181961– Moscow

Sofia, 2–4 July, 2014 CREO/Kodak EverSmart Supreme II scanners used at the Sternberg Astronomical Institute in

Sofia, 2–4 July, 2014 Basic technical characteristics of СREO/Kodak EverSmart Supreme II scanners : Type of scannerFlatbed Sensor Tri-linear 8000 element CCD Color depth 48 bit (16 bit/color) Output file format TIFF Max density 4.3 D Resolution2540 dpi Scanning area 305 x 432 mm Interface SCSI Managing computer Apple® PowerMac G5, Mac®OS® X Typical time to scan 30 x 30 cm plate 80 min Size of an output file is limited.

Sofia, 2–4 July, 2014 Scanning a plate Clean a plate and scan it to a TIFF image using software supplied with the scanner Convert TIFF to inverted grayscale and then to FITS custom tiff2fits code available at ftp://scan.sai.msu.ru/pub/software/tiff2fits/ Insert JD(mid. Exp.) to FITS header Determine a reference point at each image and cut the image into overlapping subframes ~1 degree in size Process each subframe rejecting distorted pieces closest to the edges of the plate

Sofia, 2–4 July, 2014 Images processing with VaST VaST is an open source software developed by K. Sokolovsky and A. Lebedev to search for variable objects: Works on Linux and MacOS Detects objects on a frame and performs circular aperture photometry with arbitrary zero-point using Sextractor Performs cross-matching of the objects for all plates Converts rectangular coordinates to right ascension and declination using Astrometry.net Gives magnitude calibration (USNO-B1.0 or APASS) Creates mag/RMS plot for searching possibly variable candidates Integrated with an online period search tool

Sofia, 2–4 July, 2014

β Cassiopeiae field 10 о х10 о, centered at 00 h 09 m.2, +59 o 09´ (J2000), 391 plates, m.5–16 m.5 (lower than magnitude limits of ASAS-3 and ROTSE-I/ NSVS surveys) 263 known variables and NEW : 10 Cepheids (Type I and II) 4 Delta Scuti type stars 16 high amplitude Delta Scuti type stars (HADS) !!! 679 eclipsing binaries of different subtypes 35 RR Lyrae type variables 3 BY Draconis stars 44 semiregular variables 207 irregular variables (65 yellow and 142 red stars) 2 emission-line stars Sofia, 2–4 July, 2014

Increasing number of known/discovered HADS variables In the field of β Cas (100 square degrees, less than 0.25 per cent of the overall sky area) we discovered 16 HADS variables (add 2 Delta Scuti type stars with amplitudes of 0 m.3 and more from GCVS). Expected whole-sky number: > Before our discoveries, the total number of high amplitude Delta Scuti stars with amplitudes no less than 0 m.2 in the GCVS was 121.

USNO-B – a bimodal HADS star Sofia, 2–4 July, 2014

USNO-B – a bimodal HADS star Sofia, 2–4 July, 2014

New eclipsing binaries in β Cas field From 697 eclipsing binaries discovered in β Cas field we have 346 EA,124 EB and 209 EW type stars USNO-B EAUSNO-B EB

New Cepheids in β Cas field USNO-B DCEP USNO B CW: Sofia, 2–4 July, 2014

Perspectives Publishing a new part of Moscow Digital Variables (MDV) list Digitization of plates from Moscow collection with new Epson Expression 11000XL scanner Search automatisation Competition with NSVS, ASAS-3, SuperWASP, Catalina Sky Survey etc. (?) Discoveries of transient events like faint Mira type star, dwarf novae…

Sofia, 2–4 July, 2014 Thank you for attention!