Processing of Digital Plates1.2m of Baldone Observatory Schmidt Telescope

2017

OAP

ABSTRACT. This study was aimed to estimate the precision of the selected plate processing method and test the accuracy of the Epson Perfection V700 Photo scanner used to digitize astroplates from the Odessa Astronomical Observatory's collection. The processing of astroplates was performed using specific software developed in the LINUX/MIDAS/ROMAFOT environment. In order to estimate the repeatability of the scanner's astrometric and photometric errors, six consecutive scans of one and the same plate (No 17,000 -the Pleiades star cluster) were processed in two scanning modes with spatial resolutions of 1,200 and 2,400 dpi. The plate was exposed for 30 minutes with the fourth tube of the Seven Wide Angle (SWA) astrograph. The scan size was 18 x 24 cm (13 x 18 degrees). The following estimates of the scanner's accuracy were obtained for the stars brighter than B < 13 m in the two scanning modes: 1) σ xy = ± 0.023 px, σ m = ± 0.013 m ; 2) σ xy = ± 0.082 px, σ m = ± 0.042 m for the Cartesian coordinates and instrumental magnitude, respectively.

Section: Scanning Results At 1200 and 2400 Dpimentioning

confidence: 99%

On the Digitisation of Odessa Collection of Astronomical Negatives. Examination of the Epson Perfection V700 Photo Scanner

2017

OAP

“…In particular, it was used for the determination of B magnitudes for 387 plates obtained on the fourth tube of 7-camera telescope of Odessa observatory at Mayaki observational site during 1966-1998(Kashuba, 2019. It was also applied for the determination of U and V magnitudes of stars from 300 plates and 2200 films exposed on 1.2m Schmidt telescope at Baldone observatory (Eglitis, 2019). Analogous works on the determination of U, B, V, R stellar magnitudes in frameworks of some current observational projects at different observatories are in their progress.…”

Section: Discussionmentioning

confidence: 99%

Photometry of Stars for Astronegatives With a Single Exposure

Eglitis

Protsyuk

et al. 2019

OAP

The paper discusses the construction of characteristic curves for various astronegatives with a single exposure. Particular attention is paid to the question of extrapolation of the characteristic curve for the region of the weakest stars in the absence of standards. A new method for constructing an individual characteristic curve for digitized films and plates in the UBVR system has been proposed and implemented. The processing of frames of digitized plates and films with sky areas is carried out using LINUX/MIDAS/ROMAFOT software tools. ROMAFOT application allows us to extract astrometric rectangular coordinates X,Y and photometric characteristics such as instrumental photometric magnitudes m, FWHM, and the intensity in the center of the star image Ic for all fixed objects on each astronegative. For all frames, the connection between instrumental photometric values m with stellar magnitudes in any system (Johnson UBVR, Tycho-2 or GAIA catalogs, etc.) is not linear and multipurpose. It is presented as the characteristic curve for each astronegative. In general, the characteristic curve is approximated by a 5-degree polynomial and should take into account the color equation and the photometric field error. In practice, the most and the sometimes unsolvable problem is the lack of photometric standards for the flat part of the characteristic curve (the region of faint and extremely faint stars). As a rule, the photometric standards for characteristic curve restoration from astronegatives, exposed in Johnson U, B, V or R bands (hereafter U, B, V, R ), are photoelectric data of stars in the same system. The present work concentrates on the issue of a correct definition of stellar U, B, V, R magnitudes from astronegatives obtained with a single exposition in the case when photometric standards are absent for the flat part of the characteristic curve. Currently, the determination of U, B, V, R magnitudes of stars and other space objects is in progress for astronegatives with the single exposure obtained in the frameworks of selected observational projects.

“…It is used the Epson Expression 10000XL scanner to digitize the plates of the Kitab part of FON project for generating a catalog of B-magnitudes and equatorial coordinates of stars [9][10][11][12] and performing the missions of some observational programs [13][14][15]. Accuracy of astrometric and photometric characteristics of commercial scanners are explored in the reference [16,5,6,[17][18][19][20].…”

Section: Processing Of Digitized Astroplatesmentioning

confidence: 99%

Test of the scanner for expression the astrometric and photometric parameters from the digitized plates

Yuldoshev

Muminov

et al. 2022

УФЖ

This paper performs to research in detail the Epson Expression 10000XL scanner for photographic astroplate archive of the Ulugh Beg Astronomical Institute (UBAI) of the Uzbekistan Academy of Sciences. For processing the astroplates, it is used special developed software in the LINUX/MIDAS/ROMAFOT. The test plate was digitized with grayscale 8 and 16 bits with various scanner resolutions. Astronomical and photometric parameters were carried out from the plate and an evaluation of the developed method accuracy for determining rectangular coordinates and photometry. The repeatability of astrometric and photometric errors of the scanner for the digitized resolutions, 6 successive scans of every plate with a spatial resolution 600, 900, 1200, 1500, 1800, 2100, 2400 and 2540 dpi were processed.