A Survey of Galaxies on the UK Schmidt-CalTech Asteroid Survey (UCAS) Plates Brian A. Skiff Lowell Observatory 1400 West Mars Hill Road Flagstaff AZ 86001-4499 e-mail: bas@lowell.edu preparation history: 7 Feb 1987: original catalogue draft. 24 Mar 1987: typo corrections and some new identifications. 1 Jul 1989: description and portion of catalogue published in "Webb Society Quarterly Journal" (WSQJ, no. 77, pg. 1 [July 1989]). 8 Aug 1990: a few typo corrections from HGCorwin. 15 Sep 1996: complete revision with 0'.1 positions for J2000, matched against NED database. 7 Jan 1997: added positions from USNO A1.0 catalogue. 17 Mar 1997: this introduction composed. Abstract Accurate (0'.1) positions, identifications, morphological types, descriptions, plus some dimensions and position angles are given for about 1500 galaxies in a ~500 square degree region in Leo, Virgo, Corvus, and Crater. The work was done on a set of deep UK Schmidt plates mostly of 'sky survey' quality taken for an asteroid survey. Plate Material The plates used in this survey were taken from a collection exposed in late February/early March and in May 1981 with the 1.2-meter UK Schmidt telescope at Siding Spring Observatory, near Coonabarabran, New South Wales, Australia. The plates were taken specially for a survey of main-belt asteroids conducted by my colleague Schelte J. `Bobby' Bus. Other plates taken in the survey during late March and April all overlap with these fields. Twenty-six 14x14-inch plates are included in the galaxy survey from a total of about 85. They are all IIIa-J + GG395 (not GG385) hyper'd by techniques usually used at the UK Schmidt Telescope Unit. The exposures were usually 70 minutes for plates in the western section, and 45 minutes for the eastern section. Most are of "sky survey" quality (images 40 microns or smaller), though some have rather dense (logD ~1.5) sky fog. A complete plate list is shown at the end of this note. The plates cover an irregularly-rectangular area with corners near: Survey limits: 12h47m +2.6 10h57m +10.6 (2000) 12h51m -21.9 11h00m -13.8 The asteroid project resulted in first orbits for over 1200 new asteroids as faint as mag. 21, including the only large sample of main-belt objects in the 1km size range known at that time. Survey Procedure The plates were scanned on a light-table between January and November 1986. The galaxies were examined and measured using a 7x loupe containing a reticle marked with both a scale showing 0.1-mm increments and a protractor with which sizes and position angles were determined. Galaxies were selected as follows: I measured dimensions and determined morphological types for all NGC/IC objects and selected other "large, bright" galaxies south of about +2.5 Dec identified from the Dixon et al. (1981) overlays for the POSS-I prints. Types only were determined for most other readily classifiable galaxies appearing in some catalogue, and for those anonyma south of about -2.5 Dec likely to have been within CGCG limits but not appearing in the MCG or ESO catalogues. Types only were also determined for all catalogued galaxies north of about +2.5 Dec. The survey includes a total of about 1500 objects, one-third of which are described fully by dimensions, type, and verbal description. Objects were identified using the Dixon overlays, thus errors of identification are possible, compounded from the MOL (Dixon & Sonneborn 1980). However, I usually based the catalogue name on the preferred one in the NED database, so most gross errors should have been rooted out. Occasional identities are noted in remarks when the identification is either possibly ambiguous, when I have used an old name from the literature, or when the ID appears to be new. In general, I have used the following priority for names: NGC/IC, UGC, CGCG, MCG, ESO, and "other", the last applying only to very small and/or faint objects. In the "other" names category, I have usually used the earliest name assigned in the literature where a reasonably accurate (~1') position was supplied, and the object described as nebulous or as a galaxy. I have thus frequently used names from the lists of Reinmuth, Reiz, Svenonius, and others that were published early in the 20th Century. When a modern identity can also be made (such as with the Lick Northern Proper Motion Survey [NPM1G] of reference galaxies), these are given in the notes. Galaxy Classifications I used the Hubble Atlas (Sandage 1961) and Revised Shapley-Ames catalogue (RSA, Sandage & Tammann 1981) photographic atlases with RC2 types marked alongside the photos to keep my morphological types system from drifting too much. There are clear inconsistencies in the revised system, in van den Bergh's luminosity class system (van den Bergh 1960a,b, 1966), and in the luminosity class system of the RSA: I tried to maintain a mean, weighted by types from the RC2. This approach was evidently successful. Buta et al. (1994) and Odewahn & de Vaucouleurs (1992) include a statistical analysis of my UCAS types against the high-weight paradigms ("standards") used to produce the classifications for galaxies in the RC3 (de Vaucouleurs et al. 1991). Both papers show that my types and DDO luminosity classes have relatively small scatter compared to other classifiers. The types show no significant zero-point or scale error; my DDO classes have a small zero-point offset (0.6 units in L too luminous). This offset was applied to the types that appear in the RC3, but is uncorrected for here. (About 1000 of the galaxy types here are merged into the RC3; I am source F.) A few remarks about the types are nevertheless in order. I was relatively conservative in assigning (R) and (r) when they were almost-complete or weak. Nevertheless I did have a tendency to assign (r) to S0 galaxies having a lens- shaped core with a bright disk-like collar, even though the (s) variety might be indicated by arms or spiral arcs. Buta & Crocker's (1991) refinement of outer-ring classifications was not published at the time these plates were examined, but I have amended the notation to show (R'1) or (R'2) if this was described explicitly in the notes or was plainly evident from inspection of the Digitized Sky Survey images I used to check positions. Luminosity class VI was reserved for only the most diaphanous objects, notably the few Karachentseva (1968) "Sculptor-type" dwarves, many of which are dwarf irregulars, not spheroidals. There are few true ellipticals: most objects show more-or-less well- defined inner disk-like features. Objects exhibiting boxy outer isophotes (cf. Merritt & Hernquist 1991, Kormendy & Bender 1996) or rectangular bulges (cf. Jarvis 1986, de Souza & dos Anjos 1987) are noted in the remarks. Catalogue Preparation The present version of the catalogue was prepared by searching the NED database for each object either by name or approximate position. Ambiguous cases were often re-examined on POSS-I prints or the POSS-II J films. I also made extensive use of the Digitized Sky Survey as available from the Goddard SkyView facility (http://skview.gsfc.nasa.gov), which allows a coordinate grid and catalogue files to be overlain on the image. Names were assigned based on the most common one used in NED. Objects that were not found in NED or one of the historical catalogues were assigned a name based on the J2000 position. Most of the objects had only arcminute-precision positions in NED (taken from the CGCG or MCG). Because many fields were quite crowded, I examined every object lacking a position in NED with a nominal error smaller than 5" using SkyView together with the GSC lookup feature in the SIMBAD database. This allowed GSC identifications to be made, and the GSC position to be verified as pertaining to the center of the galaxy involved (and not a superposed star or a piece of the galaxy). I also sought positions in the USNO-Flagstaff A1.0 catalogue, which contains some 500,000,000 objects as faint as mag. 20 in the red. The astrometric net for A1.0 is the GSC with a modification for radial errors on the Schmidt plates, so is not of high precision, but comparable to the GSC itself. In a minority of cases---almost always for merged pairs or for the faintest dwarf galaxies---I have estimated positions directly from the SkyView images at large scale. These are indicated with an asterisk following the position. All positions are recorded to a precision of 1s in RA and 0'.1 in Dec, and should also be reliable to +/- one unit in each coordinate, any error being due simply to roundoffs. About 90% of the galaxy positions are quoted directly from the GSC, NPM1G, A1.0, or other high-accuracy source. About 10% of the galaxies were classified on more than one plate: these have been averaged in final catalogue. Catalogue Format The first column shows the galaxy positions in the format hhmmss+ddmm.m for equinox 2000. Next come the preferred names, as described above. To avoid ambiguity when components are close or interacting, I have applied a 'specifier' usually indicating the compass direction [e.g. MCG -02-28-30 (W)], but sometimes a simple alphabetic sequence [e.g. UGC 6067 (A)]. Column 3 shows the galaxy classifications. The types are on the RC3 system as much as possible. A major exception is that the transition between E and S0- has been treated as a full subtype. The DDO classes have not been corrected for the systematic offset mentioned above. Colons and question marks are applied as necessary to appropriate features. The degree of uncertainty is a strong function of the number of resolution elements in the image, as per the discussion in the RC2. There are lots of small, faint galaxies in the list; they have lots of colons and question marks applied to their types. An underline follows dominant family (AB) or variety (rs) for transitional cases, some of these resulting from the averaging process. For example, a type containing A_B indicates an object with weak indications of barring, whereas (r_s) is a galaxy with a nearly complete inner ring. It seems that luminosity classes for objects where the stage is uncertain (colon or question mark) should also be at least as uncertain, but this is not always the case, nor so indicated. The ellipticities of ellipticals were computed in the usual way from the measured dimensions when available, and may shift when the data are reduced to the standard system. I suspect that the axis ratios are too large, as is common in visual measurements, making the ellipticity values too large (i.e. too flat). The two columns following the type, T and L, are the simply the stage and DDO class in the numerical code system of the RC3. The Hubble 'T' stages are coded from -6 (for cE) to +11 (for cI); T = -4 is used for the E/S0- transition. The DDO classes are coded from L = I to VI. Refer to the RC3 Table 2 (page 15) and page 18 for complete transit tables. The dimensions are usually given to tenths of an arcminute, sometimes to 0.05 arcmin for small objects and to 0.05 or 0.01 for ring sizes (in the notes), or to whole arcmin for the largest objects. Colons are used for uncertainty greater than about 10%, and a question mark for truly approximate sizes. In the manner of the UGC, square brackets are placed around dimensions refers to the combined extent of an interacting object where the borders between/among components are not readily distinguishable. Simple comparisons of my sizes against published surface photometry indicates the sizes are for light levels near the blue mag. 26.5/square arcsec isophote, but with a fair bit of variation due to exposure depth and base fog (see plate log). Position angles are given in the last column. A colon indicates uncertainty greater than about 5 degrees. Square brackets are again used for interacting objects. For 34 objects with position angle measured on two or more plates, the mean difference is 0.0 degrees, with sigma of 4.2 degrees. Remarks It's been said of Nilson's UGC that the most important part of the catalogue is the notes. That might not apply here, but the notes file is three-quarters the length of the main file, so there's a lot of additional information here that's not readily tabulated. The remarks include measures of the rings, discussion of the relative size and brightness of nuclei, cores, arms, morphological characteristics and peculiarities, group relationships, the presence of plumes, bridges, merger "ripple shells," etc. Alternate names and GSC IDs are given as well. In general, I have aped the approach of both Nilson and Corwin in constructing the notes, and many of their notational conventions were adopted as well. Nearly all the objects have a note, so there is no marker for them in the catalogue. Plate Catalogue The information below was taken from photocopies of the UK Schmidt plate log. The central fog is the density for the central of the nine points on each plate at which this is measured. The image diameter is in microns. The sky brightness is in units of J (blue-green) magnitudes/square arcsec, as measured by the photoelectric guiding device. An average is given if start and end values are indicated. "Mag Range" is the range in brightness of the guide star measured on a strip chart recorder with the guider. The diaphragm aperture is very small, so the range is influenced by seeing as well as clouds and the change in airmass during the exposure. Under photometric conditions and in good seeing, the value is normally 0.2. When two examination dates for a plate are given, the first is for the measures of the bright objects, the second for typing the fainter ones. Otherwise, all were done together. Some additional general comments are given in many cases. The plates are listed in the order they were examined. Plate Center Central Image Sky Mag Number RA(1950)Dec Exp Fog Diam Brtns Range (min) (DN) (mu) (mag) J6968 11 08.0 + 1.7 70 1.14 40 21.04 0.2 examined 9Jan, 28Mar, 5Aug 1986. J6961 11 09.0 - 4.35 70 1.52 65 20.86 0.3 examined 12Jan, 17Jun 1986. rather dense plate with soft images. J6967 11 08.0 -10.3 70 1.09 45 21.03 0.2 examined 14Jan, 17Jun 1986. J6986 11 32.0 - 0.9 70 1.20 40 21.13 0.2 examined 14Jan, 17Jun 1986. J6984 11 32.0 - 6.9 70 1.46 35 20.93 0.2 examined 22Jan, 23Jun 1986. emulsion flaws, but few near galaxies. continuous sheet of clusters and distant groups of galaxies across this field, richer on south half. only brighter companions noted. J6978 11 33.0 -12.9 70 1.26 40 20.96 0.2 examined 23Jan, 23Jun 1986. airmass = 1.3 at end of exp (40 degrees zenith distance). J6971 11 42.0 - 0.9 70 1.29 35 20.99 0.1 examined 7Feb, 23Jun (for types eastward of 11h43m) 1986. J6972 11 42.0 - 6.9 70 1.32 40 21.14 0.1 examined 12Mar, 23Jun 1986. J6973 11 43.0 -12.9 70 1.16 40 21.16 0.2 examined 12Mar, 23Jun 1986. examined eastward of 11h40m. J6966 11 08.0 + 7.7 70 1.35 35 20.79 0.2 examined 28May 1986. star images double. J6702 12 00.1 + 2.1 45 -- -- 21.28 0.4 examined 29May 1986. fog level low; images a little soft. J6726 12 07.5 + 2.4 45 -- -- 21.36 - examined 29May 1986 eastward of 12h10m. fog level low; good images. J6790 11 42.0 + 5.1 65 1.61 40 20.88 0.2 examined 29May 1986. sky brightness declined from 20.3 at start: twilight during first 20 minutes of exposure; dark plate! only east half examined. J6955 11 34.0 + 5.0 70 1.31 35 20.99 0.2 examined 29May 1986. J6714 11 58.8 - 3.8 45 -- -- 21.25 0.2 examined 21Jul 1986. fog level low; good images. J6700 11 59.3 -15.9 45 -- -- 21.25 0.3 examined 22Jul 1986. fog level low; images soft. examined westward of 12h00m. J6701 11 59.8 - 9.9 45 -- -- 21.07 0.2 examined 22Jul (west half), 5Aug (east half) 1986. fog level low; images soft. taken through very thin clouds? J6712 12 08.0 -15.8 45 -- -- 21.31 0.3 examined 2Aug 1986. examined eastward of 12h00m. fog level low; good images. J6719 12 22.0 - 6.3 45 -- -- 21.29 0.25 examined 2Aug 1986. fog level low; good images. Abell 1517 appears to comprise at least two groups. centered at overlay position is relatively nearby group or poor cluster, while ~10' NNE is distant rich cluster. J6713 12 23.3 -12.4 45 -- -- 21.35 0.2 examined 4Aug 1986. fog level low; good images. J6715 12 22.8 - 0.4 45 -- -- 20.96 ~1.0 examined 8Aug 1986. fog level low; good images. clouds last 10m of exposure. Abell 1530 misplotted (RA error) = Zw1220.2+0225. J6705 12 24.9 -18.5 45 -- -- 21.15 0.4 examined 9Aug 1986. fog level low; good images. rich anon cluster of galaxies at 12h36m -19o15' (1950); about 10' diameter. J6720 12 31.4 - 0.3 45 -- -- 21.24 - examined 22,23,24Oct 1986. fog level variable but low; good images. Jupiter and Saturn appear on this plate. Jupiter was covered by a square Inconel chip; nevertheless, a few galaxies are wiped out by the large overexposed regions and by various spikes and ghost reflections. about 50% overlap here with J6715. rich field near supergalactic plane and downtown Virgo cluster. J6721 12 32.0 - 6.3 45 -- -- 21.14 - examined 31Oct 1986. remeasured bright galaxies west half to compare with J6719; full survey east of 12h30m. J6709 12 34.1 -18.4 45 -- -- 21.20 0.3 examined 2Nov 1986. fog level low; images slightly fuzzy. remeasured bright galaxies west half; full survey east of 12h35m. J6718 12 32.4 - 6.3 45 -- -- 21.16 0.3 examined 2Nov 1986. fog level low; images a little soft. remeasured bright galaxies west half to compare with J6713; full survey east of 12h30m. Acknowledgements I am grateful to Bobby Bus for allowing me to examine these plates. Harold Corwin provided friendly help and interest all along the way. Jay Gallagher provided encouragement for me to undertake and complete the project. 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