(1) Atlas and Catalog of Dark Clouds Based on the 2 Micron All Sky Survey
We release an atlas and catalog of dark clouds derived based on the 2 Micron All Sky Survey Point Source Catalog (2MASS PSC). Color excess maps of E(J-H) and E(H-KS) as well as extinction maps of AJ , AH, and AKs covering all of the sky have been produced at a grid of 1'. On the basis of the E(J-H) and AJ maps, we have carried out a systematic survey for dark clouds all over the sky. In total, we identified 7614 dark clouds, and measured the coordinates, extents, and AV values for each of them. These cloud parameters are compiled into a new catalog of dark clouds, which was published in a special issue of the Publications of the Astronomical Society of Japan (PASJ) in 2011 January (Dobashi et al. 2011, PASJ, vol.63 SP1, pp.S1-S362). Electronic version of the paper can be found at http://pasj.asj.or.jp/v63/v63s1.html. Please look into the paper for detailed explanations of the data.
After releasing the extinction and color excess maps on our website in 2010, we found that the maps had some problem in the determination of the background. We later corrected this problem by utilizing the Besançn Galaxy Model (Robin et al. 2003, A&A, vol. 409, p. 523) with a great help of Dr. Douglas J. Marshall, for which our extinction and color excess maps have been improved very much. Details of the correction are fully described in a subsequent publication (Dobashi et al. 2013, PASJ, vol.65 No.2, article No. 31).
The atlas and catalog derived from the 2MASS PSC mainly trace relatively dense regions in dark clouds revealing a number of dense cloud cores leading to star formation, while those we derived previously from the optical database Digitized Sky Survey I (DSS, Dobashi et al. 2005, PASJ, vol.57, SP1, pp.S1-S386) are more suited to trace less dense regions and to reveal the global extents of dark clouds. The two datasets are complementary, and all together, they are useful to picture the structures of dark clouds in various density ranges.
(2) Data released on this website
The atlas and catalog of dark clouds based on the 2MASS PSC are released in FITS and text files on this website. We have drawn maps in the atlas at the 1’ and 15’ grid. Maps drawn at the 15’ grid have a constant angular resolution of 1 degree, while those drawn at the 1’ grid have a changing angular resolution from 1’ to 12’ depending on regions in the sky to achieve a constant noise level over a large region. For details, please see our original paper in PASJ.
As summarized in the following tables, we release the maps drawn at the 1’ grid in FITS format on this website together with some other related data such as the angular resolutions and noise levels. They can be found at http://darkclouds.u-gakugei.ac.jp/2MASS/all.html. List of the identified clouds is also released in a text file (ascii) which can be found at http://darkclouds.u-gakugei.ac.jp/2MASS/cloud_list.txt.
(3) Policy and Copyright
Copyright of the text and FITS data on this website entirely belongs to Tokyo Gakugei University. However, the data can be used by anyone for astronomical researches and education purposes.
(4) Additional Information and Request to Users
We request users of the data released on this website to refer to our paper "Dobashi et al. 2011, PASJ, Vol.63 SP1, pp.S1-S362" when they use the data for publications (papers or articles). This is important not only for us but also for users, because your referring to the paper would greatly encourage us to find a financial support to maintain and develop this website. We would very much appreciate your contribution.
We have done our best to guarantee the high quality of the data, but there might be some errors. If you should find an error, please let us know via e-mail (firstname.lastname@example.org), so that we can revise the data immediately.
(5) Contact Address
If you have a question, suggestion, or request about the data, please send an e-mail to me Kazuhito DOBASHI (email@example.com).
This website is financially supported by Grant-in-Aid for Scientific Research (Nos. 178059, 188065, 198049, 208040, 218044, 228037, 248028, 258031, 15HP8026 and 16HP8023) of Japan Society for the Promotion of Science (JSPS).
Abstract of the paper
This paper presents an atlas and catalog of dark clouds derived based on the 2Micron All Sky Survey Point Source Catalog (2MASS PSC). Color excess maps of
E(J-H) and E(H-Ks) as well as extinction maps of AJ , AH, and AKs covering all of the sky have been produced at a grid of 1'. Maps drawn at a lower grid of 15' were also derived for various sets of the threshold magnitudes in the J, H, and Ks bands to estimate the background star colors and star densities needed to derive the color excess and extinction maps. The maps obtained in this work are presented on various scales in a series of figures that can be used as an atlas of dark clouds for general research purpose. On the basis of the E(J-H) and AJ maps drawn at the 1' grid, we have carried out a systematic survey for dark clouds all over the sky. In total, we identified 7614 dark clouds, and measured the coordinates, extents, and Av values for each of them. We also searched for their counterparts in the previously published catalog of dark clouds based on the optical photographic plates DSS (Dobashi et al. 2005, PASJ, vol.57, SP1, pp.S1-S386). These cloud parameters including the information of the counterparts are compiled into a new catalog of dark clouds.
The atlas and catalog organized in this paper mainly trace relatively dense regions
in dark clouds revealing a number of dense cloud cores leading to star formation, while
those presented by Dobashi et al. (2005) based on the optical database are more suited to
trace less dense regions and to reveal the global extents of dark clouds. These two
datasets are complementary, and all together, they are useful to picture the structures
of dark clouds in various density ranges.