Who are we? A collection of astronomers, mostly amateurs, working together informally and communicating over the Internet. None of us receives any money for the effort we put into our survey, and we are not supported by any money from the US government. This project is our hobby, really.
What are we doing? Mapping bright stars, of sixth to fourteenth magnitude, in a region around the celestial equator. We measure the position and brightness of each star in several different passbands (Johnson V and Johnson-Cousins R and I) Our goal is to place all of our measurements into a single database which anyone may access via the World-Wide Web.
How do we do it? Tom Droege has built 7 "triplets", each of which contains 3 Kodak KAF-0400 CCD cameras on a single mount. He has distributed them to members around the country, who place them in their backyards and point them at the celestial equator. Each camera makes a continuous drift-scan image of the sky. We have written software to identify stellar sources and measure their properties.
Does it work? Look at the rest of this poster and decide for yourself.
http://www.tass-survey.org
Tom Droege is currently constructing the first of a series of new CCD cameras: the Mark IV. Built around a Loral 2Kx2K chip, the Mark IV will have a field of view of about 6 degrees. Unlike the Mark III, it will be operated in point-and-shoot mode, so we are designing a mount and control system for it. The Mark IV will be able to view all areas of the sky overhead, not just the strip around the celestial equator. It will reach about fourteenth magnitude from backyard sites.
We haven't quite filled in a complete strip around the celestial equator. The figure below shows the distribution of one star in every fifty in our catalog. As you can see, there is a gap between Right Ascensions of 180 to 260 degrees. We will try to fill in that gap this autumn.
Our cameras can measure accurately the properties of stars between seventh and fourteenth magnitude. We scan the sky in three passbands: V, R and I. Only one triplet has an "R" filter, so there are fewer observations in it than in V or I. Note that the V-band measurements reach to a slightly larger magnitude than R or I.
What is the use of all this information? One thing we can do is study variable stars -- stars which brighten and fade over periods of a few hours to a few days. TASS is best suited to measuring stars with periods of several weeks or months. In addition to measuring the brightness of variable stars, we can improve the positions of many stars in old catalogs of variables.
First, take a look at TASS measurements of stars which have been discovered to vary by previous surveys: R Ceti, X Ceti, Z Ceti, DH Orionis and FN Orionis.
But TASS has also discovered some stars which are previously-unknown variables. We need to acquire more observations of each of the candidates below (another year should help a lot), but these are just a small fraction of all the new variable stars which we can pull out of our database. It will be a lot easier after we perform a final photometric calibration.
Here's a list of new variable-star candidates; it is by no means exhaustive or complete.
# new variable star candidates from the Dayton TASS dataset # # coordinates are equinox J2000. Listed magnitudes are those of # the first detection of the star (not the mean value). # # RA Dec V I comments 0.4112 -3.7564 12.71 9.67 LPV, period ~120 days 0.5812 -1.5154 14.52 13.64 2.3474 -1.5749 14.29 13.88 2.9506 -1.4379 11.23 10.28 7.0912 -2.3230 14.59 14.08 11.2894 -2.2661 14.35 14.18 14.6167 -1.6636 7.71 6.73 14.8471 -4.2818 12.64 11.78 short period 15.4730 -2.5412 13.88 13.50 40.0094 -2.9301 10.29 9.80 40.6497 -3.0734 12.79 9.15 42.2359 -4.0906 10.14 9.32 44.0787 -2.3482 9.61 8.99 45.5023 -2.9403 8.95 8.42 45.5464 -3.9596 10.11 9.37 292.7657 -2.6774 11.27 7.58 294.8458 -4.4109 11.06 7.54 295.7640 -4.1515 13.15 9.01 295.8184 -3.3978 13.71 10.06 LPV, amp > 1 mag in V 299.6186 -2.4580 12.91 9.27 LPV, amp > 1 mag in V 299.9719 -3.9990 13.32 7.22 305.3077 -4.2125 10.04 6.86 305.5477 -2.3577 14.27 13.86 305.7769 -3.6896 11.84 8.28 308.7154 -2.7153 12.31 8.12 period ~80? days 310.7576 -1.7471 9.60 7.13 312.0801 -2.2664 12.75 9.32 313.8522 -2.3609 11.79 9.38 314.7909 -4.1855 8.65 7.89 315.1558 -1.8752 13.93 12.91 315.3574 -3.8867 11.43 8.32 315.7433 -1.6308 10.24 7.79 315.8776 -3.6964 10.81 9.48 315.9872 -2.1676 10.14 9.43 LPV, small amplitude? 317.2910 -2.5739 10.87 8.68 317.4305 -2.3398 11.33 10.35 317.9650 -1.7527 10.78 8.49 322.3323 -2.2350 12.44 9.52 323.5841 -2.4658 10.98 8.58 326.9826 -2.6153 11.07 8.21 327.7030 -3.0308 13.80 12.81 328.1159 -1.9146 14.47 13.57 328.4519 -3.1744 9.76 8.23 328.8980 -3.0120 10.43 9.62 329.3700 -4.1722 10.68 6.71 LPV 330.3240 -3.5130 14.56 13.24 334.1850 -2.5185 11.03 9.44 334.2107 -3.7786 12.75 9.62 338.8844 -2.9418 7.99 6.88 339.5198 -2.0895 10.66 9.68 340.5238 -3.4441 11.27 10.74 relatively sharp peak? 341.3167 -2.2268 12.83 12.00 348.3155 -2.7363 11.34 7.63 348.8592 -2.8784 13.86 12.88 350.6029 -2.2283 11.51 10.25 small amplitude? 357.6848 -3.1220 14.18 14.18 357.8123 -2.7639 12.94 10.62