Intermediate Astrometry Data (IAD) Residual records for the Hipparcos Re-reduction (van Leeuwen, 2007) Source: Hipparcos-2 Interactive Data Access Tool (2014) Acknowledgements: Floor van Leeuwen Daniel Michalik 3 September 2021 This ASCII dataset was exported from the Hipparcos-2 Interactive Data Access Tool (IDAT; https://www.cosmos.esa.int/web/hipparcos/interactive-data-access; "the Java tool"). The astrometric solution provided in the tool is self-consistent, but not numerically identical to the data provided on the DVD that accompanied the Hipparcos Re-reduction book by van Leeuwen (2007; hereforth Hip2-DVD). The format of the exported files mimics the format of the residual records that were provided on the Hip2-DVD (see book, Table G.8). However, additional header lines are available containing more auxiliary information as well as the reference astrometric parameters. Furthermore, the residual records now indicate which transits were rejected in the final astrometric solution (SRES <= 0). Byte-by-byte description of the data -------------------------------------------------------------------------------- Line 7 (first header line, excluding comments/labels in the count) The same fields and format as the header in Hip2-DVD Table G.8. Two columns have been renamed to better match the data they contain: NRES instead of NOB, F1 instead of NR. Data taken from the (binary) epoch astrometry files provided with the Java tool. -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 3 - 8 I6 HIP Hipparcos identifier 10 - 15 I6 MCE Main-catalogue entry (1) 17 - 19 I3 NRES Number of residual records (2) 22 - 22 I1 NC Number of components 25 - 27 I3 isol_n Solution type (3) 32 - 35 I4 SCE Supplement-catalogue entry 37 - 42 F6.2 F2 Goodness of fit 44 - 45 I2 F1 Percentage rejected (4) -------------------------------------------------------------------------------- Note (1): The MCE field in the Hip2-DVD data internally used an unsigned short integer, which led to an overrun from index 32767 to -32768 when read with a signed short. This was corrected here. Note (2): NRES corresponds to the number of residual records available for this source. The residual record file of a given source is therefore always (13 + NRES) lines long: 13 header lines including comments/labels, plus the actual residual records. Note (3): See van Leeuwen (2007), Section 3.5, for a discussion of the different solution types. Note (4): F1 was stored as an integer in the epoch astrometry headers. That means the number given is the actual percentage rounded down to the nearest integer. -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- Line 9 (second header line, excluding comments/labels in the count) Contains auxiliary information. Data taken from the main astrometric catalogue files provided with the Java tool (binary files). -------------------------------------------------------------------------------- 3 - 9 F7.4 mag Hp Hp magnitude, see ESA (1997), Field H44 11 - 16 F6.3 mag B-V B-V colour index, see ESA (1997), Field H37 18 - 18 I1 VarAnn Reference to variability annex, see ESA (1997), Field H53 25 - 27 I3 NOB Number of observations (1) 29 - 31 I3 NR Number of rejected observations (2) -------------------------------------------------------------------------------- Note (1): The number of observations processed in the astrometric solution of this source, including the NR rejected observations. For most sources NOB is identical to the number of residuals available (first header line, field NRES). For 6617 sources the two numbers differ. This indicates some data corruption in the residual records of these sources. See Brandt et al. (2021), Section 4, for a detailed discussion. These authors also offer an ad-hoc correction to the residual records for the 6617 sources affected. Note (2): The number of observations rejected in the astrometric solution of this source. These are marked with negative/zero sigma abscissa residuals (SRES) in the residual records. Note that there are currently 89 sources where NR does not equal the number of records with negative/zero sigmas. Since the origin of this issue is not understood, these should be treated with extra care. -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- Line 11 (third header line, excluding comments/labels in the count) Contains the reference astrometric parameters, against which the residuals are expressed, and their corresponding uncertainties. Data taken from the main astrometric catalogue files provided with the Java tool (binary files). All sources list the five main astrometric parameters (and their uncertainties) first. Sources with 7/9 parameter or VIM solutions additionally list the higher order terms of their astrometric solution (and the corresponding uncertainties). Sources with stochastic solutions additionally list the cosmic dispersion parameter. The solution type is given in the first header line, field isol_n modulo 10, i.e. by the least significant digit of isol_n. Additional fields that are not applicable are marked with "---". Note: For sources with a 7 parameter, 9 parameter, or VIM solution, the residuals are relative to the full 7 parameter, 9 parameter, or VIM solutions. This is in contrast to the original Hipparcos reduction (ESA, 1997), where the residuals are always defined with respect to the skypath described by only the first five parameters, regardless of solution type. -------------------------------------------------------------------------------- 3 - 14 F12.8 deg RAdeg Right Ascension 16 - 27 F12.8 deg DEdeg Declination 29 - 36 F8.2 mas Plx Parallax 38 - 45 F8.2 mas/yr pmRA Proper motion in Right Ascension 47 - 54 F8.2 mas/yr pmDE Proper motion in Declination 56 - 61 F6.2 mas e_RA Formal error on RAdeg 63 - 68 F6.2 mas e_DE Formal error on DEdeg 70 - 75 F6.2 mas e_Plx Formal error on Plx 77 - 82 F6.2 mas/yr e_pmRA Formal error on pmRA 84 - 89 F6.2 mas/yr e_pmDE Formal error on pmDE 91 - 96 F6.2 mas/yr2 dpmRA Acceleration in Right Ascension (7p, 9p) 98 - 103 F6.2 mas/yr2 dpmDE Acceleration in Declination (7p, 9p) 105 - 110 F6.2 mas/yr2 e_dpmRA Formal error on dpmRA (7p, 9p) 114 - 119 F6.2 mas/yr2 e_dpmDE Formal error on dpmDE (7p, 9p) 123 - 128 F6.2 mas/yr3 ddpmRA Acceleration change in Right Ascension (9p) 131 - 136 F6.2 mas/yr3 ddpmDE Acceleration change in Declination (9p) 139 - 144 F6.2 mas/yr3 e_ddpmRA Formal error on ddpmRA (9p) 149 - 154 F6.2 mas/yr3 e_ddpmDE Formal error on ddpmDE (9p) 159 - 164 F6.2 mas upsRA VIM in Right Ascension (VIM) 167 - 172 F6.2 mas upsDE VIM in Declination (VIM) 175 - 180 F6.2 mas e_upsRA Formal error on upsRA (VIM) 184 - 189 F6.2 mas e_upsDE Formal error on upsDE (VIM) 193 - 198 F6.2 mas var Cosmic dispersion added (stochastic) -------------------------------------------------------------------------------- Note (7p, 9p): Applicable to 7p and 9p solutions only; isol_n ending in 7 or 9. "---" for all other solution types. Note (9p): Applicable to 9p solutions only; isol_n ending in 9. "---" for all other solution types. Note (VIM): Applicable to VIM solutions only; isol_n ending in 3. "---" for all other solution types. Note (stochastic): Applicable to stochastic solutions only; isol_n ending in 1. "---" for all other solution types. -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- Line 14 and all subsequent lines Residual records: "NRES" data records per source. The same fields (in the same order) as the data records in Hip2-DVD Table G.8. Minor format changes in the field width and the number of significant digits of EPOCH and PARF. Data taken from the (binary) epoch astrometry files provided with the Java tool. -------------------------------------------------------------------------------- 3 - 6 I4 IORB Orbit Number 8 - 14 F7.4 yr-1991.25 EPOCH Epoch 16 - 22 F7.4 PARF Parallax factor 24 - 30 F7.4 CPSI cos(psi) (1) 32 - 38 F7.4 SPSI sin(psi) (1) 40 - 46 F7.2 mas RES Abscissa residual 48 - 53 F6.2 mas SRES Formal error on abscissa residual (2) -------------------------------------------------------------------------------- Note (1): The Hipparcos-2 angle psi is related to the Gaia scan angle theta as theta = pi/2 - psi. See Brandt et al. (2021), Section 2. Note (2): Rejected observations are marked as negative or zero (0.00) values. -------------------------------------------------------------------------------- References: - ESA, 1997, The Hipparcos and Tycho Catalogues, ESA SP-1200 - van Leeuwen, F. 2007, Hipparcos, the New Reduction of the Raw Data: Astrophysics and Space Science Library, Volume 350. ISBN 978-1-4020-6341-1. Springer Science+Business Media B.V., 2007. doi:10.1007/978-1-4020-6342-8 - G. M. Brandt, D. Michalik, T. Brandt, Y. Li, T. Dupuy, Y. Zeng 2021, HTOF: A new open-source tool for analyzing Hipparcos, Gaia, and future astrometric missions, AJ, in press