GRB 250610B: Swift observation summary

This is a confirmed GRB (GRB 250610B), the afterglow is source 1 -- please see the GRB results at https://www.swift.ac.uk/xrt_products/00019863 for updated analysis

Mission:	SVOM/ECLAIRs
SVOM RA:	200.174°
SVOM Dec:	+31.175°
SVOM Err:	3.9 arcmin
T0:	2025-06-10 16:33:19 UT
Galactic:	67.03° +82.44°
Galactic N_H:	1.08× 10²⁰ cm^-2

Sun distance:	101.97°
Sun angle:	8.09 [hr] (East of Sun)
Moon distance:	75.49°
Visibility of this field.
First slew:	2025-06-10 17:19:52 UT
First observation:	2025-06-10 17:19:18 UT
First analysis:	2025-06-10 22:41:31 UT

Data analysed so far:

ObsID: 00019863001 with 2.0 ks exposure.
ObsID: 00019863002 with 2.9 ks exposure.

About tiled field analysis.

So far 1 fields have been scheduled for observations. Data are available and processed for 1 of these.

19863 — 5.0 ks of cleaned data taken between 2025-06-10 17:19:48 and 2025-06-11 21:55:13

Details of afterglow candidates

1 sources were found which matches the afterglow criteria.

#	RA (J2000)	Dec (J2000)	Err₉₀¹	Detection Flag²	Rank³	Dist from SVOM/ECLAIRs pos	Exposure	Notes	Vizier
1 [details]	13h 20m 43.13s200.17969°	+31° 06′ 17.2″31.10478°	2.7′′ ^*	Good	2 (O)	4.2′	5.0 ks	The source is fading with 4.1-σ significance. The source is 4.9-σ above the RASS limit.
Mean XRT rate: 5.1 (±0.4) ×10^-2 ct s^-1 Peak XRT rate: 0.138 (±0.023) ct s^-1 RASS PSPC 3-σ upper limit: 0.03 ct s^-1 (PSPC count-rate) Mean XRT rate converted to PSPC: 0.086 (±0.006) ct s^-1 Peak XRT rate converted to PSPC: 0.23 (±0.04) ct s^-1 Mean XRT flux: 1.81 (±0.13) ×10^-12 erg cm^-1s^-1 Peak XRT flux: 4.9 (±0.8) ×10^-12 erg cm^-1s^-1 Products: Light curve \| Spectrum \| Enhanced position

¹ Radius, 90% confidence.
² Indicates how likely the source is to be real. See the LSXPS documentation.
³ T=Transient Source, O=Outbursting known source, U=Uncatalogued X-ray source, K=Known X-ray source.
^* The position was enhanced using astrometry derived from the Swift UVOT.
^† The position was astrometrically corrected using the XRT sources and the 2MASS catalogue.

Find an upper limit.

Sources found so far

So far 7 sources have been found in the XRT data. 6 sources match catalogued sources.

#	RA (J2000)	Dec (J2000)	Err₉₀¹	Detection Flag²	Rank³	Dist from SVOM/ECLAIRs pos	Exposure	Notes
1 [details]	13h 20m 43.13s200.17969°	+31° 06′ 17.2″31.10478°	2.7′′ ^*	Good	2 (O)	4.2′	5.0 ks	The source is fading with 4.1-σ significance. The source is 4.9-σ above the RASS limit.
Mean XRT rate: 5.1 (±0.4) ×10^-2 ct s^-1 Peak XRT rate: 0.138 (±0.023) ct s^-1 RASS PSPC 3-σ upper limit: 0.03 ct s^-1 (PSPC count-rate) Mean XRT rate converted to PSPC: 0.086 (±0.006) ct s^-1 Peak XRT rate converted to PSPC: 0.23 (±0.04) ct s^-1 Mean XRT flux: 1.81 (±0.13) ×10^-12 erg cm^-1s^-1 Peak XRT flux: 4.9 (±0.8) ×10^-12 erg cm^-1s^-1 Products: Light curve \| Spectrum \| Enhanced position
2 [details]	13h 20m 60.00s200.24999°	+31° 02′ 30.9″31.04191°	4.7′′ ^*	Good	3 (U)	8.9′	5.0 ks	Matches SIMBAD source: US 604, 0.7″ away.
Mean XRT rate: 7.1 (+1.6, -1.5) ×10^-3 ct s^-1 Peak XRT rate: 1.08 (±0.29) ×10^-2 ct s^-1 RASS PSPC 3-σ upper limit: 0.02 ct s^-1 (PSPC count-rate) Mean XRT rate converted to PSPC: 0.0128 (+0.0029, -0.0027) ×10^-2 ct s^-1 Peak XRT rate converted to PSPC: 0.020 (±0.005) ×10^-2 ct s^-1 Mean XRT flux: 2.8 (±0.6) ×10^-13 erg cm^-1s^-1 Peak XRT flux: 4.2 (±1.1) ×10^-13 erg cm^-1s^-1 Products: Light curve \| Spectrum \| Enhanced position
3 [details]	13h 20m 30.09s200.12536°	+31° 21′ 10.9″31.35303°	5.4′′	Good	4 (K)	11.0′	2.0 ks	Matches SIMBAD source: SDSS J132029.54+312113.6, 7.5″ away. Matches known X-ray source: 1RXS J132030.1+312120 (from ROSAT/RASSFSC), 9.5710641357176″ away.
Mean XRT rate: 1.08 (+0.35, -0.29) ×10^-2 ct s^-1 Peak XRT rate: 1.08 (+0.35, -0.29) ×10^-2 ct s^-1 -0.45 σ above the catalogued flux from ROSAT/RASSFSC. RASS PSPC 3-σ upper limit: 0.0×10⁰ ct s^-1 (PSPC count-rate) Mean XRT rate converted to PSPC: 0.046 (+0.015, -0.012) ct s^-1 Peak XRT rate converted to PSPC: 0.046 (+0.015, -0.012) ×10^-2 ct s^-1 Mean XRT flux: 2.2 (+0.7, -0.6) ×10^-13 erg cm^-1s^-1 Peak XRT flux: 2.2 (+0.7, -0.6) ×10^-13 erg cm^-1s^-1 Products: Light curve \| Spectrum \| Enhanced position
4 [details]	13h 20m 22.93s200.09556°	+30° 56′ 16.1″30.93780°	4.6′′ ^*	Good	4 (K)	14.8′	2.9 ks	Matches SIMBAD source: [SMB88] 1859, 9.2″ away. Matches known X-ray source: 1RXS J132023.5+305608 (from ROSAT/RASSFSC), 4.6264041939907″ away.
Mean XRT rate: 1.47 (+0.31, -0.28) ×10^-2 ct s^-1 Peak XRT rate: 1.8 (±0.5) ×10^-2 ct s^-1 0.98 σ below the catalogued flux from ROSAT/RASSFSC. RASS PSPC 3-σ upper limit: 0.0×10⁰ ct s^-1 (PSPC count-rate) Mean XRT rate converted to PSPC: 0.019 (±0.004) ct s^-1 Peak XRT rate converted to PSPC: 0.023 (±0.006) ×10^-2 ct s^-1 Mean XRT flux: 4.5 (+1.0, -0.9) ×10^-13 erg cm^-1s^-1 Peak XRT flux: 5.5 (±1.4) ×10^-13 erg cm^-1s^-1 Products: Light curve \| Spectrum \| Enhanced position
5 [details]	13h 20m 36.07s200.15031°	+30° 54′ 08.7″30.90241°	7.0′′ ^*	Good	4 (K)	16.4′	0 s	Matches SIMBAD source: PB 3514, 5.8″ away. Matches known X-ray source: 1RXH J132036.0+305414 (from ROSAT/ROSHRI), 6.4598833646629″ away.
Mean XRT rate: undetermined ct s^-1 Peak XRT rate: undetermined ct s^-1 -0.18 σ above the catalogued flux from ROSAT/ROSHRI. RASS PSPC 3-σ upper limit: 0.0×10⁰ ct s^-1 (PSPC count-rate) Products: Enhanced position
6 [details]	13h 20m 10.11s200.04214°	+31° 04′ 04.2″31.06785°	6.2′′	Reasonable	3 (U)	9.3′	5.0 ks	Matches SIMBAD source: SDSSCGB 32282.3, 3.4″ away.
Mean XRT rate: 1.5 (+0.9, -0.7) ×10^-3 ct s^-1 Peak XRT rate: 1.5 (+0.9, -0.7) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.02 ct s^-1 (PSPC count-rate) Mean XRT rate converted to PSPC: 2.6 (+1.5, -1.1) ×10^-3 ct s^-1 Peak XRT rate converted to PSPC: 2.6 (+1.5, -1.1) ×10^-3 ct s^-1 Mean XRT flux: 8 (+5, -3) ×10^-14 erg cm^-1s^-1 Peak XRT flux: 8 (+5, -3) ×10^-14 erg cm^-1s^-1 Products: Light curve \| Spectrum
7 [details]	13h 20m 36.14s200.15057°	+31° 16′ 19.2″31.27200°	6.6′′	Reasonable	3 (U)	5.9′	5.0 ks	Matches SIMBAD source: LP 323-28, 20.3″ away.
Mean XRT rate: 1.96 (+1.01, -0.76) ×10^-3 ct s^-1 Peak XRT rate: 1.96 (+1.01, -0.76) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.35 ct s^-1 (PSPC count-rate) Mean XRT rate converted to PSPC: 2.8 (+1.4, -1.1) ×10^-4 ct s^-1 Peak XRT rate converted to PSPC: 2.8 (+1.4, -1.1) ×10^-4 ct s^-1 Mean XRT flux: 2.12 (+1.09, -0.83) ×10^-12 erg cm^-1s^-1 Peak XRT flux: 2.12 (+1.09, -0.83) ×10^-12 erg cm^-1s^-1 Products: Light curve \| Spectrum

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