{"release":{"id":"DR1","released_on":"2026-08-21","doi":null,"url":"https://spacecatalog.org/releases#dr1"},"epoch":{"requested":"now","label":"J2026.654","julian_year":2026.654,"time":"2026-08-27T21:57:40.558Z","years_from_j2000":26.654,"frame":"date","applied":"Proper motion, then precession and nutation. The catalogued J2000 position is carried along the great circle the object's own published motion puts it on, at a constant velocity, and the result is referred to the true equator and equinox of this instant. Those are separate things: the motion moves the object, and the rotation turns the grid under it by about fifty arcseconds a year, with nutation adding up to another seventeen.","excluded":"Parallax, the radial-velocity perspective term, aberration and refraction; each is below the accuracy of the catalogued positions themselves. An object with no published proper motion comes back where the catalogue has it rather than at a fabricated zero, and says so with a null pm_ra_mas_yr. A body with no fixed position is not propagated at all — its place comes from an ephemeris, which is what /api/v1/visible answers with."},"slug":"hd-17895","name":"RR Eri","class":"m5iii_red_giant","category":"star","object_type":"M5III red giant","mag":7.03,"mag_band":"V","abs_mag":-0.797,"abs_mag_band":"V","distance_ly":1199.1044641406534,"distance_method":"parallax","ra_deg":43.059105,"dec_deg":-8.267068,"epoch_ra_deg":43.38852,"epoch_dec_deg":-8.156711,"epoch_moved_arcsec":0.452,"pm_ra_mas_yr":-0.54,"pm_dec_mas_yr":-16.94,"orbits":null,"semi_major_axis_km":null,"periapsis_km":null,"mass_kg":null,"mass_msun":null,"constellation":"Eridanus","discovered":null,"featured":false,"url":"https://spacecatalog.org/object/hd-17895","radius_km":null,"radius_kind":null,"data_quality":null,"description":null,"properties":{"spectral_type":"M5III","color_index_bv":1.433,"luminosity_solar":181.46797793969282,"variability_type":"SRB","variable_mag_max":6.951,"variable_mag_min":7.321,"variability_class":"Semiregular pulsating giant (poorly defined periodicity)","radial_velocity_km_s":-9.8,"spectral_type_source":"SIMBAD (1999MSS...C05....0H, quality C)","variable_designation":"RR Eri","variable_period_days":97,"proper_motion_ra_mas_yr":-0.54,"proper_motion_dec_mas_yr":-16.94},"designations":[{"catalog":"HD","designation":"HD 17895"},{"catalog":"HIP","designation":"HIP 13384"},{"catalog":"Variable star","designation":"RR Eri"}],"source":{"id":"hyg","name":"HYG Database v4.1","url":"https://github.com/astronexus/HYG-Database","license":"CC-BY-SA-4.0"},"updated_at":"2026-08-27T19:16:43.430Z","variability":{"type":"SRB","class":"Semiregular pulsating giant (poorly defined periodicity)","period_days":97,"epoch_hjd":null,"epoch_marks":"maximum","mag_brightest":6.951,"mag_faintest":7.321,"phase":{"at":"2026-08-27T21:57:40.558Z","at_hjd":2461280.417428,"event":"maximum","value":null,"uncertainty":null,"uncertainty_days":null,"cycles_since_epoch":null,"next":[],"unavailable":"For this class the published period is a mean cycle time rather than an ephemeris: the star repeats on that timescale without keeping to it, so counting cycles from a past event would predict a date the star has no obligation to meet.","applied":"The whole cycles between the published epoch and the instant asked for, counted at the published period. Both are on the same heliocentric scale: the instant is corrected for where the Earth was in its orbit, which is worth up to 8.3 minutes and is the difference between an eclipse timed in January and one timed in July.","excluded":"Any change in the period since it was measured. The uncertainty here is the published precision of the period carried through the cycles since the epoch, plus that of the epoch itself; it is not an error bar the upstream catalogue published, and where that catalogue has flagged a period as doubtful the true figure is larger. Nothing at all is claimed for classes whose period is a mean cycle time — a dwarf nova, an irregular or a semiregular variable gets elements and no phase, and says so."}},"attribution":"Data from SpaceCatalog.org. Individual records carry their source and license in `source`; attribution is required for CC-BY and CC-BY-SA rows."}