EP250704a: Swift observation summary

This is a confirmed GRB (GRB 250704B), the afterglow is source 2 -- please see the GRB results at https://www.swift.ac.uk/xrt_products/00019908 for updated analysis

Mission:	Einstein Probe/WXT
Einstein Probe RA:	300.872°
Einstein Probe Dec:	+12.030°
Einstein Probe Err:	3.1 arcmin
T0:	2025-07-04 08:16:52 UT
Galactic:	52.10° -10.03°
Galactic N_H:	9.66× 10²⁰ cm^-2

Sun distance:	141.10°
Sun angle:	10.84 [hr] (West of Sun)
Moon distance:	97.71°
Visibility of this field.
First slew:	2025-07-04 08:46:40 UT
First observation:	2025-07-04 08:46:13 UT
First analysis:	2025-07-04 11:41:13 UT

Data analysed so far:

ObsID: 00019908001 with 1.7 ks exposure.

About tiled field analysis.

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

19908 — 1.7 ks of cleaned data taken between 2025-07-04 08:46:42 and 2025-07-04 09:18:12

Details of afterglow candidates

1 sources were found which matches the afterglow criteria.

#	RA (J2000)	Dec (J2000)	Err₉₀¹	Detection Flag²	Rank³	Dist from Einstein Probe/WXT pos	Exposure	Notes	Vizier
2 [details]	20h 03m 29.18s300.87158°	+12° 01′ 23.9″12.02331°	3.6′′	Reasonable	2 (O)	0.4′	1.7 ks	The source is 4.1-σ above the RASS limit.
Mean XRT rate: 0.247 (±0.017) ct s^-1 Peak XRT rate: 0.39 (±0.09) ct s^-1 RASS PSPC 3-σ upper limit: 0.03 ct s^-1 (PSPC count-rate) Mean XRT rate converted to PSPC: 0.316 (±0.021) ct s^-1 Peak XRT rate converted to PSPC: 0.50 (±0.11) ct s^-1 Mean XRT flux: 8.8 (±0.6) ×10^-12 erg cm^-1s^-1 Peak XRT flux: 1.4 (±0.3) ×10^-11 erg cm^-1s^-1 Products: Light curve \| Spectrum

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 2 sources have been found in the XRT data. 1 sources match catalogued sources.

#	RA (J2000)	Dec (J2000)	Err₉₀¹	Detection Flag²	Rank³	Dist from Einstein Probe/WXT pos	Exposure	Notes
1 [details]	20h 03m 18.52s300.82718°	+12° 09′ 49.0″12.16362°	3.9′′	Good	3 (U)	8.4′	1.7 ks	This source may be affected by optical loading Matches SIMBAD source: Gaia DR3 1805949089882861568, 1.2″ away.
Mean XRT rate: 2.0 (±0.5) ×10^-2 ct s^-1 Peak XRT rate: 2.0 (±0.5) ×10^-2 ct s^-1 RASS PSPC 3-σ upper limit: 0.03 ct s^-1 (PSPC count-rate) Mean XRT rate converted to PSPC: 0.033 (±0.008) ct s^-1 Peak XRT rate converted to PSPC: 0.033 (±0.008) ×10^-2 ct s^-1 Mean XRT flux: 7.5 (±1.7) ×10^-13 erg cm^-1s^-1 Peak XRT flux: 7.5 (±1.7) ×10^-13 erg cm^-1s^-1 Products: Light curve \| Spectrum
2 [details]	20h 03m 29.18s300.87158°	+12° 01′ 23.9″12.02331°	3.6′′	Reasonable	2 (O)	0.4′	1.7 ks	The source is 4.1-σ above the RASS limit.
Mean XRT rate: 0.247 (±0.017) ct s^-1 Peak XRT rate: 0.39 (±0.09) ct s^-1 RASS PSPC 3-σ upper limit: 0.03 ct s^-1 (PSPC count-rate) Mean XRT rate converted to PSPC: 0.316 (±0.021) ct s^-1 Peak XRT rate converted to PSPC: 0.50 (±0.11) ct s^-1 Mean XRT flux: 8.8 (±0.6) ×10^-12 erg cm^-1s^-1 Peak XRT flux: 1.4 (±0.3) ×10^-11 erg cm^-1s^-1 Products: Light curve \| Spectrum

Image

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FITS image.

Exposure map

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FITS exposure map.