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The revision of the MASS/DIMM star catalogue
N. Shatsky, V. Kornilov March 16, 2008
Abstract The compilation of the (updated) version of the MASS (MASS/DIMM) device target catalogue is described. The new catalogue of 119 stars is presented together with criteria of star selection discussed in details. The comparison with previous version of the target catalogue is given.

With the expansion of the MASS-DIMM turbulence characterization technology, the need to revise the star catalogue of the device has b ecome evident. Application to the measurements of atmospheric extinction, misidentification problems due to imp erfect p ointing of the feeding telescop e, occasional lack of targets, red stars too faint for the measurements, etc have forced the MASS group to recompile the list of stars to b e used with the device (esp ecially in rob otic mode). The original list was compiled in early 2000-s given more or less the same ideas as follow here except that the fact of the MASS band b eing significantly bluer than Johnson's V was not taken into account. Meanwhile, a small effort has b een made to clean the resulting list as a few exp erimental devices existing that time were used in manual mode only. With the advent of the numerous and automatic astroclimate monitors, the need for the thoughroughly refined catalogue b ecome evident, but the observers put almost no attention to the p otential problems coming from "bad stars". The exp erience with the e.g. Tololo data processing and installation of the own astroclimatic facility of the MASS group home institution at Caucasus has revealed the drawbacks of the list and gave birth to the new catalogue describ ed here. As input catalogue, the Bright Stars (5th Revised Ed., Hoffleit et al, 1991) is again taken, from which all stars down to Vmag=3.4 were extracted (260 ob jects). Then the list was cleaned according to following criteria: I. Remove stars too faint for a MASS device. The device has the sp ectral band in b etween the Johnson's B and V bands). Here the color equation of the Sternb erg device was taken: M AS S mag = V mag + 0.45 (B - V ); stars with M AS S mag > 3.2 were removed. This relation is somewhere in the middle of the range of the color equation slop es of other MASS devices (0.35 for MASS/DIMMs with filters to 0.6-0.8 in ESO MASS/DIMMs) so this filtering has not removed their p otential targets. I I. The double stars with comp onent V-magnitude difference less than 4 and separation b etween 0.3 arcsec and 4 arcmin were rejected. (Fainter stars does not introduce much light; closer 1


pairs scintillate synchronously; wider pair companions cannot drop into the MASS ap erture simultaneously). The information on duplicity is collected from the BS catalogue itself and its notes. I I I. Comp osite sp ectrum ob jects and 2 M-giants were removed since their sp ectral energy distributions cannot b e represented by any of the "normal" ones used in MASS data processing. IV. Stars revealing the large (> 0.2) formal color excess due to imp erfectly determined sp ectrum class or strong interstellar absorption were also removed as those with warp ed sp ectral energy distribution. V. Strongly (Vmax - Vmin > 0.3) variable stars were removed as making the extinction control violated and since their sp ectra and colors are also varying with time. Low-amplitude variables are left in the list with the notes (see b elow). This was made based on the GCVS4.2 catalogue data. VI. A few targets were dropp ed which have close (< 1 degree) and brighter neighb our which can cause misidentification and p ointing errors. In ma jority of such cases, the neighb ouring stars are b etter MASS targets. The search for close (BS) ob jects was made using VizieR service of CDS; its results on relatively bright neighb ours are presented in the notes to the star list (see b elow). As a result of filtering presented ab ove, the cleaned list contains 119 stars. We have to note that DIMM measurements demand only the criterion I) and partly I I) to b e fulfilled for successful seeing measurements. So, the list for the standalone DIMM measurements is more reach and may b e compiled separately, given its own field of view and color sensitivity constraints. Compared to the initial MASS star catalogue, 34 stars were removed and 22 added. Among removed, 21 star are faint (> 2.7V) red stars which have too low count in MASS ap ertures. Among 13 others, Zet UMa and Gam Cen are close doubles; Ups Sco removed b eing too close to Lam Sco; Bet Per, Eps Per are bright strong variables; 6 other removed variables are faint (> 2.8V); Zet Per and Zet Oph removed due to strong color excess. Among stars added to the initial catalogues, there are 3 bright (Bet Ori, Bet Tau and Eps CMa) and 3 moderately bright (Alp And, Zet Pup and Alp UMi) stars. Half (11) of news are added blue stars with MASS mag 3.1-3.2. They can b e measured with enough precision on clear skies when no other bright target available. The sp ectral treatment might seem too complicated for such a "robust" technique as scintillations analysis. Meanwhile, sp ecial effort was made to study the role of the sp ectral band and uncertainties in its knowledge in the turbulence profile restoration (see http://dragon.sai.msu.ru/ mass/download/doc/mass spectral band eng.pdf). So, the observes are warned once again to maintain the correct color resp onse curve of their device in the processing of the MASS data. The new version of the MASS (MASS/DIMM) star catalogue is presented with the following table structure (we give the field name and the FORTRAN-like format; the fields are separated with a single space: 2


F H N R R R D D D V B S S F

DESCRIPTION -------------------------------------------------------------Bright Stars catalogue number Star name (from BS field, spaces replaced with underscore) Right ascension hour, J2000 Right ascension minute, J2000 Right ascension second, J2000 Declination degree with sign symbol, J2000 Declination arcminute, J2000 Declination arcsecond, J2000 Johnson V-band magnitude Johnson B-V color Spectrum Energy Distribution code (see Turbina description) Spectral type from BS Flags: 'N' - close (<10') neighbour, '1' - variable ampl 0.04-0.09V, '2' - var. 0.1-0.19V, '3' - var. 0.2-0.27V NOTES C35 Close duplicity, variablity, neighbours distance, direction and V-magnitudes (found in 3x3 degree square) ----------------------------------------------------------------------------

i R a A A A E E E M V E P L

eld TYPE -----------I4 me C7 H2000 I2 M2000 I2 S2000 I2 CD2000 C3 CM2000 I2 CS2000 I2 AG F5.2 F5.2 D C3 TYPE C13 C2

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Figure 1: Distribution of MASS star catalogue stars on the sky. The stars added to the list are shown in red, removed targets are op en circles. The size of the symb ol denotes the MASS magnitude.

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