IRTS/NIRS Point Source Catalogue (version 1) Tanaka, M.(*), Murakami, H., Freund, M. M., Matsuura, M., Noda, M., Matsumoto, T., Yamamura, I., Le Bertre, T., Cohen, M. (*) Email: masa@ir.isas.ac.jp * Executive summary -------------------- The NIRS Point Source Catalogue (PSC) contains point source fluxes observed with the NIRS (Near InfraRed Spectrometer; Noda et al. 1994) which is one of the four focal-plane instruments of the IRTS (InfraRed Telescope in Space; Murakami et al. 1994). The IRTS mission was performed during the 4-week period in March and April 1995 and surveyed two strips (called as `north scan' and `south scan', respectively), which covered about 7% of the sky (Murakami et al. 1996). The NIRS was primarily designed to measure the absolute diffuse sky brightness with a beam of 8'x8' with low dispersion (~0.1 micron). However, the NIRS obtained useful data for studies on the stars; it measured spectra of many point sources in the wavelength range of 1.4-4 micron, where ground observation is partly prohibited by the atmosphere. Spectra obtained with the NIRS clearly show molecular bands such as H2O, CO, C2H2 typical to late type stars (Matsuura et al. 1999; Le Bertre et al. 2001). In the NIRS PSC version 1, 14,223 objects confirmed by at least double detection are catalogued. Positions, magnitudes in pseudo-H,K,L bands and associations with IRAS and Tycho catalogued are also presented. The NIRS PSC may be revised in future due to error correction, improved processing, addition of objects and so on. Please find the latest information from the DARTS WWW site at the ISAS: http://www.darts.isas.ac.jp/. * File list ------------ README.txt This file NIRSPSC.dat The NIRS PSC in ASCII format hist_mag.ps Histogram of H,K,L magnitude hist_mag_2mass.ps Histogram of difference in H,K magnitude from 2MASS hist_pos.ps Histogram of difference in position from other catalogues * Descriptions on the NIRS data reduction and processing --------------------------------------------------------- Flight performance of the NIRS observation is described by Noda et al. (1996). Post flight calibration is described by Murakami et al. (2001) and Matsuura et al. (2001). An overview of processing the NIRS PSC is described by Freund et al. (1997). Detailed description of processing and characteristics for this catalogue will be appeared in the near future. * NIRS Instrument Characteristics ---------------------------------- Beam size: 8'x8' Characteristics of NIRS spectral channels: ------------------------------------- c-1 col-2 col-3 col-4 col-5 ch wavelen bandwid noise 0-mag micron micron Jy Jy ------------------------------------- 24 1.386 0.108 0.145 1344. 23 1.486 0.115 0.151 1212. 22 1.588 0.114 0.144 1077. 21 1.691 0.117 0.129 990.4 20 1.795 0.115 0.119 914.3 19 1.898 0.119 0.127 831.8 18 2.002 0.115 0.118 764.9 17 2.106 0.117 0.124 703.0 16 2.209 0.114 0.129 641.9 15 2.312 0.113 0.135 597.3 14 2.415 0.112 0.214 552.7 13 2.518 0.109 0.150 510.8 12 2.860 0.108 0.245 409.1 11 2.962 0.108 0.303 386.5 10 3.065 0.112 0.283 358.9 9 3.167 0.111 0.329 343.0 8 3.269 0.113 0.520 321.1 7 3.370 0.110 0.524 304.5 6 3.472 0.115 0.476 289.6 5 3.575 0.109 0.546 274.4 4 3.675 0.113 0.880 259.5 3 3.778 0.110 0.555 243.6 2 3.878 0.106 0.597 234.7 1 3.977 0.107 0.657 224.1 ------------------------------------- Column-1: Channel number (numbered in descending order of wavelength). Column-2: Wavelength of band center weighted by system transmittance. Column-3: Band width. Column-4: Typical RMS noise of output signal for point source extraction. Column-5: Flux of zero magnitude in NIRS channel band. Note: The channel characteristics above are derived assuming that objects are scanned at the center of the NIRS beam. The observed wavelengths shift depending on the cross-scan position. Multiple detection of the same object may reduce this uncertainty (see also the description on `position' below). * Catalogue Format ------------------- The NIRS PSC data are stored in `NIRSPSC.dat' file in ASCII format. Each line of this file contains catalogue data of a object in the format of the next table. Length of each line is 754 bytes including newline code (0x0A). First line is a header which shows the data format. Following the header line, catalogue data are listed in the order of North-scan and South-scan, and then, Right Ascension (J2000). -------------------------------------------------------------------- Field Bytes Format Description -------------------------------------------------------------------- 1 1- 10 a10 NIRS PSC name (IRAS conventions) 2 12- 12 a1 N-scan (N) or S-scan data (S) 3 14- 29 a16 RA-Dec (J2000) in format of |00h03.0m +74d04'| 4 31- 36 f6.2 Right Ascension (J2000) (degrees) 5 38- 43 f6.2 Declination (J2000) (degrees) 6 45- 49 f5.1 Position Angle (degrees) 7 51- 56 f6.2 Galactic Longitude (degrees) 8 58- 63 f6.2 Galactic Latitude (degrees) 9 65- 70 f6.2 In-scan position (degrees) in IRTS coordinate 10 72- 77 f6.2 Cross-scan position (degrees) in IRTS coordinate 11 79- 82 f4.1 In-scan error (arcmin) 12 84- 87 f4.1 Xross-scan error (arcmin) 13 89- 94 f6.3 H_nirs magnitude 14 96-101 f6.3 K_nirs magnitude 15 103-108 f6.3 L_nirs magnitude 16 110-114 f5.3 H_nirs magnitude error 17 116-120 f5.3 K_nirs magnitude error 18 122-126 f5.3 L_nirs magnitude error 19 128-138 e11.4 Flux24 : F_nu (Jy) of ch24 (lambda=1.4 micron) 20 140-150 e11.4 Flux23 21 152-162 e11.4 Flux22 22 164-174 e11.4 Flux21 23 176-186 e11.4 Flux20 24 188-198 e11.4 Flux19 25 200-210 e11.4 Flux18 26 212-222 e11.4 Flux17 27 224-234 e11.4 Flux16 28 236-246 e11.4 Flux15 29 248-258 e11.4 Flux14 30 260-270 e11.4 Flux13 31 272-282 e11.4 Flux12 32 284-294 e11.4 Flux11 33 296-306 e11.4 Flux10 34 308-318 e11.4 Flux9 35 320-330 e11.4 Flux8 36 332-342 e11.4 Flux7 37 344-354 e11.4 Flux6 38 356-366 e11.4 Flux5 39 368-378 e11.4 Flux4 40 380-390 e11.4 Flux3 41 392-402 e11.4 Flux2 42 404-414 e11.4 Flux1 : F_nu (Jy) of ch1 (lambda=4.0 micron) 43 416-423 e8.2 Flux_err24 : Error in Flux F_nu (Jy) of ch24 44 425-432 e8.2 Flux_err23 45 434-441 e8.2 Flux_err22 46 443-450 e8.2 Flux_err21 47 452-459 e8.2 Flux_err20 48 461-468 e8.2 Flux_err19 49 470-477 e8.2 Flux_err18 50 479-486 e8.2 Flux_err17 51 488-495 e8.2 Flux_err16 52 497-504 e8.2 Flux_err15 53 506-513 e8.2 Flux_err14 54 515-522 e8.2 Flux_err13 55 524-531 e8.2 Flux_err12 56 533-540 e8.2 Flux_err11 57 542-549 e8.2 Flux_err10 58 551-558 e8.2 Flux_err9 59 560-567 e8.2 Flux_err8 60 569-576 e8.2 Flux_err7 61 578-585 e8.2 Flux_err6 62 587-594 e8.2 Flux_err5 63 596-603 e8.2 Flux_err4 64 605-612 e8.2 Flux_err3 65 614-621 e8.2 Flux_err2 66 623-630 e8.2 Flux_err1 67 632-633 i2 Ndata24 : Num of Event data for ch24 68 635-636 i2 Ndata23 69 638-639 i2 Ndata22 70 641-642 i2 Ndata21 71 644-645 i2 Ndata20 72 647-648 i2 Ndata19 73 650-651 i2 Ndata18 74 653-654 i2 Ndata17 75 656-657 i2 Ndata16 76 659-660 i2 Ndata15 77 662-663 i2 Ndata14 78 665-666 i2 Ndata13 79 668-669 i2 Ndata12 80 671-672 i2 Ndata11 81 674-675 i2 Ndata10 82 677-678 i2 Ndata9 83 680-681 i2 Ndata8 84 683-684 i2 Ndata7 85 686-687 i2 Ndata6 86 689-690 i2 Ndata5 87 692-693 i2 Ndata4 88 695-696 i2 Ndata3 89 698-699 i2 Ndata2 90 701-702 i2 Ndata1 91 704-705 i2 Num of Events used in this source 92 707-708 i2 Num of nearby event groups 93 710-710 i1 Num of association with IRAS PSC 94 712-712 i1 Num of association with 2MASS cat 95 714-714 i1 Num of association with Tycho cat 96 716-716 i1 Num of association with Hipparcos cat 97 718-727 a10 NIRS name of associated PS in the other scan 98 729-738 a10 IRAS PSC name 99 740-751 a12 Tycho Identifier 100 753-753 i1 Reset mode: 1m (0), 1s (1), mix (2) -------------------------------------------------------------------- Note: The flux errors here come from the signal noise and the fluctuation of baseline. In addition to this, there are two kinds of uncertainty. One is calibration errors. Another is uncertainty in the cross-scan position in the NIRS aperture (see below). Both uncertainties are estimated to be about +/- 10%, respectively. * Position ----------- We define the `IRTS coordinate' for the north- and south-scan respectively, so that IRTS scan paths are close to its equator. In-scan and the cross-scan positions correspond to longitude and latitude of the IRTS coordinate, respectively. To convert B1950 coordinate to the IRTS coordinate, you rotate around the Z axis by A and then rotate by D around the Y axis. The values of A and D are: A (degree) D (degree) N scan 2.25 106.25 S scan 25.0 64.0 (RA,Dec)=(182.25,-73.75) and (25.0,-64.0) (degrees) are converted to (lon,lat)=(0,0) in the IRTS north-scan and south-scan coordinate, respectively. The IRTS pointing reconstruction is performed using data of the star sensor on the focal plane, by collaborating with the IPAC. Thus defined positions have errors of ~1' in in-scan direction and ~2' in cross-scan direction. The systematic offset of the NIRS position is corrected using cross-identified objects with other catalogues; Hipparcos, Tycho, 2MASS, IRAS PSC. Cross-scan position of single detection has additional uncertainty up to the NIRS aperture size, +/- 4', since we do not know the exact position where the objects passed in the field of view. However, multiple detection of the same object alleviates this uncertainty. Errors in cross-scan position are reduced for objects detected with wide range in cross-scan direction. * NIRS H,K,L band ------------------ The magnitudes of NIRS H,K,L bands are calculated from summation of fluxes (in lambda*F_lambda) of the following NIRS channels: H_NIRS: ch20-ch23 (1.486, 1.588, 1.691, 1.795 micron) K_NIRS: ch14-ch18 (2.002, 2.106, 2.209, 2.312, 2.415 micron) L_NIRS: ch3- ch8 (3.269, 3.371, 3.472, 3.575, 3.676, 3.778 micron) Invalid data (due to under detection limit or data lost) have magnitude = 99.0 and magnitude error = 9.0. * Cross ID statistics ---------------------- scan=N+S ---------------------- Hipparcos : 3165 Tycho : 9433 2MASS : 4736 IRAS PSC : 5665 ---------------------- Entries : 14294 ---------------------- dupl.in N&S : 72(N), 71(S) (*) Total obj. : 14223 (*) 18487+2940 and 18491+2940 in N-scan are both associated with 18489+2938 in S-scan. scan=N ---------------------- Hipparcos : 704 Tycho : 3050 2MASS : 1334 IRAS PSC : 2605 No assoc. : 996 ---------------------- Entries : 5735 scan=S ---------------------- Hipparcos : 2461 Tycho : 6383 2MASS : 3402 IRAS PSC : 3060 No assoc. : 579 ---------------------- Entries : 8559 * Reference ------------ Murakami, H. et al. 1994 ApJ. 428, 354 Noda, M. et al. 1994 ApJ. 428, 363 Murakami, H. et al. 1996 PASJ 48L, 41 Noda, M. et al. 1996 SPIE 2817, 248 Freund, M.M. et al. 1997 `Diffuse Infrared Radiation and the IRTS' ASP Conf. Series Vol. 124, Ed. H. Okuda; T. Matsumoto; and T. Rollig, p.67 Matsuura, M. et al. 1999 A&A 348, 579 Le Bertre, T. et al. 2001 A&A 376, 997 Murakami, H. et al. 2001 `The calibration legacy of the ISO Mission' ESA Special Publ. Series Vol. 481, Ed. L. Metcalfe and M. F. K. Kessler Matsuura, M. et al. 2001 `The calibration legacy of the ISO Mission' ESA Special Publ. Series Vol. 481, Ed. L. Metcalfe and M. F. K. Kessler