skrutski@north.phast.umass.edu schneide@wilt.phast.umass.edu huchra@fang.harvard.edu roc,tchester,jarrett Extended Source Guild, Chester and I have been hatching a plan to build a galaxy cluster catalog based on the 2MASS extended source database/catalog. Our preliminary foray into this field would suggest that indeed we can find clusters and we can predict their redshift as well. The paper I presented at the San Diego AAS touched on the methodology. A more "evolved" description can be found in the link given below (more specifically, it is a proposal to do the job; the Sci team has of course final say on this matter). The catalog will be similar to what the DPOSS (POSS II people) will generate, but I suspect we will find clusters that they cannot discern (thanks to our infrared eyes). I have an algorithm and software package in place now that can find clusters. The link below describes this system and it presents some case studies of known clusters (ABell 3558, Herc, Coma) as well as a random field chosen from our RTB dataset. The random field contains what I believe to be the first 2MASS cluster (it cannot be found in the literature, but perhaps John Huchra has a secret list somewhere of identified clusters :). Comments welcome. -tj http://spider.ipac.caltech.edu/staff/jarrett/2mass/3chan/redshift/gz_cat.html ___________ 2MASS comrads, I would like to open dialogue on planning a series of papers to be submitted to one of the big journals (ApJ or AJ). I believe the time has come that we publish our "early" 2MASS extended source results to contrast/complement the "review" and "preliminary" papers we have been publishing in various conference and seminars/workshops proceedings over the years. With the imminent data release later this summer of a small smackeral of data and of a considerably larger sample next spring, these papers will provide a useful guide/supplement to would-be user of the 2MASS galaxy data set. Given the exceedingly slow turn around for an ApJ paper (we can look forward to at least 8 months of waiting) the series would appear in the journals around the time of the data release. I envision at least three separate papers (or one large paper divided/published in separate parts) : 1. basic extended source results 2. color-photometric results for a cluster 3. preliminary redshift results The first paper serves as an "introduction" to the 2MASS extended source database (not unlike the reviews that we have been generating over the years, see e.g. Schneider's nice summary given at the Paris workshop, but with more emphasis on the large area survey results -- we have results over 180 sq. degrees of data fully analyzed). Basic photometric sensitivity results, completeness & reliability and source counts would provide the guts of the results (the latter plot will be unprecidented in the near-IR). This paper will probably serve as the primary "cite" or "reference" paper for future papers by our group and others using 2MASS data. Tom Chester gave a nice poster at the San Diego AAS that basically encapulates this "paper" that needs to be written up for the journals. The second paper is a more specific topic relating to the photometric/color results for a targeted cluster (e.g., Hercules). I gave a poster at the AAS that might serve nicely as a template for this paper. This kind of paper serves as a more detailed/focused use of the 2MASS data. It could also foreshadow the 2MASS galaxy cluster catalog that we (Jarrett/Chester) have proposed to build. There may of course be other specific topics that we might want to write up as part of this "early" series of 2MASS extended source science (e.g., Steve might be ready to publish some results on Tully-Fisher). The third paper might serve as an introduction to the large-scale structure key project buttressed by the massive redshift survey that John is directing. By now we have obtained enough redshift data to gauge our ability to measure the local angular correlations between clusters and superclusters. Let me be clear that I am not suggesting that we publish prematurely, indeed the key projects themselves have just begun, but rather I believe the "basic" results are in-house and ready to go prime-time (ApJ). With the data release next spring, the "basic" data results will provide a logical supplement to the large data set (which I bet the would-be user will require some time to digest and dissect the rather extensive and complicated information that we will graciously supply:). With the summer months now upon us, it is time to bear down and get these papers out. Let the flow of dialogue now commence. -tj __________ from TChester, i definitely think that you ought to take the lead in writing several papers in order to get some papers out of the tremendous effort you have put into galworks. it would be good to get advice from steve and john, being our galaxy pundits, as to what would be most appropriate. i assume that john and steve will be the lead authors on the key projects, so there are plenty of first author papers to go around. some ideas: we will definitely in the end write up an expl. supp. to 2mass galaxy catalog which will probably be a web doc, and may or may not be published separately. it may be appropriate to publish a "letters" article announcing the 2mass galaxy catalog, with a brief overview of it and its characteristics (numbers, variation with latitude, completeness limits, reliability), that then points the reader to the web doc. this would then be the main scientific literature ref for users of the catalog, but users may simply point to the expl. sup. as is done for iras. i strongly feel that you ought to be the first author on that paper and exp. sup. _______ note that one really cannot write up the doc for the released catalog until we get there, so it is not practical to think about writing up a mini-exp. sup. 5 months prior to data release. therefore i amend what i said above - the letters article cannot give a brief overview of the catalog, unless we can publish it on a 1-2 month time scale. the letters article can give preliminary results a la my aas paper. title should thus be something like my aas paper: The 2MASS Galaxy Catalog: First Results rather than Overview of The 2MASS Galaxy Catalog or The 2MASS Galaxy Catalog since we simply won't know for sure what will be in the galaxy catalog for some time. thus this paper will only be a reference for the selected items it contains - the main ref has got to be the expl. sup. there definitely ought to be a scientific overview paper published much like my paper at the first iras conference, which goes more into the scientific content, such as log n / log s numbers, redshift distribution, types of galaxies represented, etc. this probably would not get referenced nearly as much as the exp. supp. or its letters announcement. your cluster work is entirely separate, and is a major scientific work in its own right along with the key projects. i suggest that you publish preliminary results asap, mentioning in your paper that the catalog is available online as it is being built, with this paper announcing the first clusters found thru ir selection. then people can already start investigating if ir-defined clusters differ from optically defined clusters. making the catalog available as it is being done would be a novelty, which should result in brownie points for you and for the 2mass project. i also don't think this has much danger, since defining the clusters is pretty straightforward, and global analysis is not really needed to validate the cluster catalog. when it is all done, 3? years from now, you can publish it as an ap.j.supp. i hope by that time the ap.j. is no longer actually publishing long tables, but is simply referencing where to get that online! again, these are thoughts. comments welcome. -_____ chas paper to PASP: ABSTRACT The 2 Micron All Sky Survey (2MASS) will catalog over 100,000,000 individual objects, the vast majority of which will be stars of spectral type K and later. For many projects it will be important to develop techniques to identify interesting objects within this data set. The combination of near-IR and visible light observations will be a powerful tool for finding objects from brown dwarfs to dust-enshrouded quasars. This paper describes prototype hardware and software systems used as part of the preparation for the 2MASS survey. Three years of observations with prototype systems have produced a database of more than 1 million objects. A companion paper describes the comparison of these data with optical plate material and visible spectroscopic observations resulting in the discovery of a quasar with a redshift of 0.147. The goal of the 2 Micron All Sky Survey (2MASS) is to map the entire sky at three near-infrared wavelengths (Kleinmann et al. 1994; Skrutskie et al. 1997) with 10 sensitivity limits of 15.8, 15.1, and 14.3 mag at wavelengths of 1.25 (J), 1.65 (H), and 2.2 (Ks) m (Table 1). As part of this effort, a prototype camera incorporating a single NICMOS3 array was developed for use on the Kitt Peak 1.3 m telescope. The telescope and camera are used in a novel fashion for rapid acquisition of data with high photometric precision. A prototype data processing pipeline was developed at the Infrared Processing and Analysis Center (IPAC) with the goal of making a highly complete and reliable set of catalogs and images. The prototyping exercise has been extremely successful with many technical lessons carried over into the construction of the survey hardware (telescopes and three-channel cameras) and software. The survey goals (Table 1) have been achieved with a single-band camera, and there is every expectation that the same performance, or better, will be achieved with the survey hardware. Many of the data obtained with the prototype camera are of good quality and have been processed into a database consisting of more than 1 million individual point sources over 160 deg2 of sky. We have begun to analyze these sources to understand how the final database of more than 100,000,000 2MASS objects can be used to advance a number of scientific goals, including galactic structure, the distribution of galaxies in the local universe, and the search for rare objects such as brown dwarfs and extremely red extragalactic sources. This paper describes the systems (camera and software) used to generate these prototype data. Differences between the prototype and final systems will be briefly noted. This paper concerns results for point sources only. A companion paper describes the outcome of the comparison of 2MASS data with optical plate material and some optical spectroscopic observations. This follow-up activity led to the discovery of a quasar at z = 0.15 (Beichman et al. 1998). A related paper using the 2MASS prototype data describes the discovery of a star of very low mass (Kirkpatrick, Beichman, & Skrutskie 1997).