GRB 250527C: Swift observation summary

Mission:	Swift/BAT
GRB RA:	319.633°
GRB Dec:	+52.737°
GRB Err:	5.0 arcmin
T0:	2025-05-27 13:58:32 UT
Galactic:	93.89° +2.31°
Galactic N_H:	1.18× 10²² cm^-2
Galactic E(B-V):	3.588579

Sun distance:	81.56°
Sun angle:	6.99 [hr] (West of Sun)
Moon distance:	80.07°
Visibility of this field.

Data analysed so far:

ObsID: 00021843001 with 4.8 ks exposure.

About ToO analysis.

Find an upper limit.

Sources found so far

So far 6 sources have been found in the XRT data. 3 sources match catalogued sources.

#	RA (J2000)	Dec (J2000)	Err₉₀¹	Detection Flag²	Dist from Swift/BAT pos	Exposure	Notes
1 [details]	21h 18m 30.79s319.62830°	+52° 47′ 39.1″52.79420°	2.9′′	Good	3.4′	4.8 ks	Matches known X-ray source: 1RXS J211831.5+524742 (from ROSAT/RASSFSC), 10.7″ away. Matches SIMBAD source: TYC 3953-1190-2, 3.9″ away.
Mean XRT rate: 1.57 (+0.24, -0.23) ×10^-2 ct s^-1 Peak XRT rate: 4.3 (±0.9) ×10^-2 ct s^-1 RASS PSPC 3-σ upper limit: 0.0×10⁰ ct s^-1 (XRT equiv count-rate) Mean XRT flux: 2.7 (±0.4) ×10^-13 erg cm^-1s^-1 Peak XRT flux: 7.5 (±1.6) ×10^-13 erg cm^-1s^-1 Products: Light curve \| Spectrum \| Enhanced position \| Expected serendipitous sources: ~0.00×10⁺⁰ [What is this?] Note: this is extragalactic sources only, whereas the GRB trigger is at b=2.31°
2 [details]	21h 19m 14.43s319.81013°	+52° 46′ 06.5″52.76848°	3.8′′	Good	6.7′	4.8 ks
Mean XRT rate: 6.1 (±1.5) ×10^-3 ct s^-1 Peak XRT rate: 6.1 (±1.5) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 8.7×10^-3 ct s^-1 (XRT equiv count-rate) Products: Enhanced position \| Expected serendipitous sources: ~0.00×10⁺⁰ [What is this?] Note: this is extragalactic sources only, whereas the GRB trigger is at b=2.31°
3 [details]	21h 17m 31.67s319.38197°	+52° 43′ 06.9″52.71859°	6.6′′	Good	9.2′	4.8 ks	Matches SIMBAD source: ZTF J211731.87+524307.2, 1.9″ away.
Mean XRT rate: 3.4 (+1.3, -1.1) ×10^-3 ct s^-1 Peak XRT rate: 3.4 (+1.3, -1.1) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 420.48 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 4.9 (+1.9, -1.5) ×10^-10 erg cm^-1s^-1 Peak XRT flux: 4.9 (+1.9, -1.5) ×10^-10 erg cm^-1s^-1 Products: Spectrum \| Expected serendipitous sources: ~0.00×10⁺⁰ [What is this?] Note: this is extragalactic sources only, whereas the GRB trigger is at b=2.31°
4 [details]	21h 19m 04.71s319.76964°	+52° 54′ 37.2″52.91033°	6.3′′	Good	11.5′	4.8 ks
Mean XRT rate: 2.8 (+1.3, -1.0) ×10^-3 ct s^-1 Peak XRT rate: 2.8 (+1.3, -1.0) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.04 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 1.5 (+0.7, -0.5) ×10^-13 erg cm^-1s^-1 Peak XRT flux: 1.5 (+0.7, -0.5) ×10^-13 erg cm^-1s^-1 Products: Spectrum \| Expected serendipitous sources: ~0.00×10⁺⁰ [What is this?] Note: this is extragalactic sources only, whereas the GRB trigger is at b=2.31°
5 [details]	21h 18m 47.14s319.69643°	+52° 42′ 57.3″52.71591°	7.0′′	Poor	2.6′	4.8 ks	Matches SIMBAD source: 2MASS J21184744+5242468, 10.8″ away.
Mean XRT rate: 1.4 (+0.8, -0.6) ×10^-3 ct s^-1 Peak XRT rate: 1.4 (+0.8, -0.6) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 9.24 ct s^-1 (XRT equiv count-rate) Mean XRT flux: 5.4 (+3.3, -2.5) ×10^-11 erg cm^-1s^-1 Peak XRT flux: 5.4 (+3.3, -2.5) ×10^-11 erg cm^-1s^-1 Products: Spectrum \| Expected serendipitous sources: ~0.00×10⁺⁰ [What is this?] Note: this is extragalactic sources only, whereas the GRB trigger is at b=2.31°
6 [details]	21h 19m 38.45s319.91022°	+52° 40′ 30.1″52.67503°	5.9′′	Reasonable	10.7′	4.8 ks
Mean XRT rate: 1.84 (+1.06, -0.78) ×10^-3 ct s^-1 Peak XRT rate: 1.84 (+1.06, -0.78) ×10^-3 ct s^-1 RASS PSPC 3-σ upper limit: 0.02 ct s^-1 (XRT equiv count-rate) Products: Expected serendipitous sources: ~0.00×10⁺⁰ [What is this?] Note: this is extragalactic sources only, whereas the GRB trigger is at b=2.31°

¹ Radius, 90% confidence.
² Indicates how likely the source is to be real. See the 1SXPS documentation.
^* The position was enhanced using astrometry derived from the Swift UVOT.
^† The position was astrometrically corrected using the XRT sources and the 2MASS catalogue.

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Exposure map

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FITS exposure map.