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Home > Einstein Probe follow up > EP250321a

EP_FIELD00029

EP

29

/EP

EP250321a: Swift observation summary

Data analysed so far:

• ObsID: 00019631001 with 1.8 ks exposure.
• ObsID: 00019631002 with 2.6 ks exposure.
• ObsID: 00019631003 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.

• 19631 — 6.2 ks of cleaned data taken between 2025-03-21 07:21:37 and 2025-03-22 00:42:47

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
1 [details]	11h 57m 02.97s179.26236°	+17° 21′ 46.4″17.36288°	2.4′′ *	Good	2 (O)	1.4′	10.3 ks	The source is fading with 4.4-σ significance. The source is 4.6-σ above the LSPXS limit.
Mean XRT rate: 0.223 (±0.008) ct s-1 Peak XRT rate: 3.8 (±0.8) ct s-1 RASS PSPC 3-σ upper limit: 0.03 ct s-1 (PSPC count-rate) Mean XRT rate converted to PSPC: 0.291 (±0.010) ct s-1 Peak XRT rate converted to PSPC: 5.0 (±1.1) ct s-1 Mean XRT flux: 8.38 (±0.29) ×10-12 erg cm-1s-1 Peak XRT flux: 1.4 (±0.3) ×10-10 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 12 sources have been found in the XRT data. 3 sources match catalogued sources.

#	RA (J2000)	Dec (J2000)	Err901	Detection Flag2	Rank3	Dist from Einstein Probe/WXT pos	Exposure	Notes	Vizier
1 [details]	11h 57m 02.97s179.26236°	+17° 21′ 46.4″17.36288°	2.4′′ *	Good	2 (O)	1.4′	10.3 ks	The source is fading with 4.4-σ significance. The source is 4.6-σ above the LSPXS limit.
Mean XRT rate: 0.223 (±0.008) ct s-1 Peak XRT rate: 3.8 (±0.8) ct s-1 RASS PSPC 3-σ upper limit: 0.03 ct s-1 (PSPC count-rate) Mean XRT rate converted to PSPC: 0.291 (±0.010) ct s-1 Peak XRT rate converted to PSPC: 5.0 (±1.1) ct s-1 Mean XRT flux: 8.38 (±0.29) ×10-12 erg cm-1s-1 Peak XRT flux: 1.4 (±0.3) ×10-10 erg cm-1s-1 Products: Light curve | Spectrum | Enhanced position
2 [details]	11h 56m 30.07s179.12528°	+17° 20′ 40.1″17.34446°	7.5′′	Poor	3 (U)	8.2′	10.3 ks
Mean XRT rate: 3.31 (+1.17, -0.98) ×10-3 ct s-1 Peak XRT rate: 3.31 (+1.17, -0.98) ×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: 7.2 (+2.6, -2.1) ×10-3 ct s-1 Peak XRT rate converted to PSPC: 7.2 (+2.6, -2.1) ×10-3 ct s-1 Mean XRT flux: 7.1 (+2.5, -2.1) ×10-14 erg cm-1s-1 Peak XRT flux: 7.1 (+2.5, -2.1) ×10-14 erg cm-1s-1 Products: Light curve | Spectrum
3 [details]	11h 57m 42.05s179.42522°	+17° 28′ 06.1″17.46837°	4.0′′ *	Good	3 (U)	10.6′	9.7 ks	This source may be affected by optical loading Matches SIMBAD source: HD 103877, 1.5″ away.
Mean XRT rate: 7.0 (+1.3, -1.2) ×10-3 ct s-1 Peak XRT rate: 9.8 (±2.6) ×10-3 ct s-1 RASS PSPC 3-σ upper limit: 0.05 ct s-1 (PSPC count-rate) Mean XRT rate converted to PSPC: 0.0102 (+0.0019, -0.0018) ×10-2 ct s-1 Peak XRT rate converted to PSPC: 0.014 (±0.004) ×10-2 ct s-1 Mean XRT flux: 1.24 (±0.22) ×10-13 erg cm-1s-1 Peak XRT flux: 1.7 (±0.4) ×10-13 erg cm-1s-1 Products: Light curve | Spectrum | Enhanced position
4 [details]	11h 56m 33.06s179.13774°	+17° 13′ 30.0″17.22500°	3.1′′ *	Poor	3 (U)	12.0′	8.3 ks	Matches SIMBAD source: NVSS J115633+171331, 4.8″ away.
Mean XRT rate: 2.18 (±0.22) ×10-2 ct s-1 Peak XRT rate: 3.0 (±0.6) ×10-2 ct s-1 RASS PSPC 3-σ upper limit: 0.04 ct s-1 (PSPC count-rate) Mean XRT rate converted to PSPC: 0.032 (±0.003) ct s-1 Peak XRT rate converted to PSPC: 0.044 (±0.009) ×10-2 ct s-1 Mean XRT flux: 6.5 (+0.7, -0.6) ×10-13 erg cm-1s-1 Peak XRT flux: 8.8 (±1.9) ×10-13 erg cm-1s-1 Products: Light curve | Spectrum | Enhanced position
5 [details]	11h 57m 10.16s179.29235°	+17° 23′ 35.3″17.39313°	6.7′′	Poor	3 (U)	1.8′	10.3 ks
Mean XRT rate: undetermined ct s-1 Peak XRT rate: undetermined ct s-1 RASS PSPC 3-σ upper limit: 1.3×10-7 ct s-1 (PSPC count-rate) Mean XRT rate converted to PSPC: undetermined ct s-1 Peak XRT rate converted to PSPC: undetermined ct s-1 Mean XRT flux: undetermined erg cm-1s-1 Peak XRT flux: undetermined erg cm-1s-1 Products: Light curve | Spectrum
6 [details]	11h 56m 27.24s179.11348°	+17° 16′ 46.4″17.27956°	4.1′′ *	Reasonable	3 (U)	10.6′	10.3 ks
Mean XRT rate: 7.1 (±1.9) ×10-3 ct s-1 Peak XRT rate: 7.1 (±1.9) ×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: 0.014 (±0.004) ×10-2 ct s-1 Peak XRT rate converted to PSPC: 0.014 (±0.004) ×10-2 ct s-1 Mean XRT flux: 1.2 (±0.3) ×10-13 erg cm-1s-1 Peak XRT flux: 1.2 (±0.3) ×10-13 erg cm-1s-1 Products: Light curve | Spectrum | Enhanced position
7 [details]	11h 57m 38.62s179.41090°	+17° 27′ 33.2″17.45923°	5.2′′	Reasonable	3 (U)	9.6′	10.3 ks
Mean XRT rate: 1.6 (+0.7, -0.5) ×10-3 ct s-1 Peak XRT rate: 1.73 (+1.07, -0.76) ×10-3 ct s-1 RASS PSPC 3-σ upper limit: 0.06 ct s-1 (PSPC count-rate) Mean XRT rate converted to PSPC: 1.4 (+0.6, -0.4) ×10-3 ct s-1 Peak XRT rate converted to PSPC: 1.5 (+0.9, -0.6) ×10-3 ct s-1 Mean XRT flux: 1.6 (+0.7, -0.5) ×10-13 erg cm-1s-1 Peak XRT flux: 1.75 (+1.09, -0.77) ×10-13 erg cm-1s-1 Products: Light curve | Spectrum
8 [details]	11h 57m 08.01s179.28336°	+17° 18′ 37.1″17.31031°	5.8′′	Poor	3 (U)	4.7′	10.3 ks
Mean XRT rate: undetermined ct s-1 Peak XRT rate: undetermined ct s-1 RASS PSPC 3-σ upper limit: 0.0×100 ct s-1 (PSPC count-rate) Mean XRT flux: undetermined erg cm-1s-1 Peak XRT flux: undetermined erg cm-1s-1 Products: Light curve | Spectrum
9 [details]	11h 56m 25.56s179.10651°	+17° 31′ 58.8″17.53300°	5.2′′	Good	3 (U)	12.5′	2.8 ks	Matches SIMBAD source: LAMOST J115625.40+173157.26, 2.8″ away.
Mean XRT rate: 5.8 (+2.5, -2.0) ×10-3 ct s-1 Peak XRT rate: 5.8 (+2.5, -2.0) ×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: 7.7 (+3.3, -2.6) ×10-3 ct s-1 Peak XRT rate converted to PSPC: 7.7 (+3.3, -2.6) ×10-3 ct s-1 Mean XRT flux: 1.9 (+0.8, -0.6) ×10-13 erg cm-1s-1 Peak XRT flux: 1.9 (+0.8, -0.6) ×10-13 erg cm-1s-1 Products: Light curve | Spectrum
10 [details]	11h 56m 34.12s179.14218°	+17° 27′ 09.8″17.45273°	6.9′′	Reasonable	3 (U)	7.9′	10.3 ks
Mean XRT rate: undetermined ct s-1 Peak XRT rate: undetermined ct s-1 RASS PSPC 3-σ upper limit: 0.0×100 ct s-1 (PSPC count-rate) Mean XRT flux: undetermined erg cm-1s-1 Peak XRT flux: undetermined erg cm-1s-1 Products: Light curve | Spectrum
11 [details]	11h 57m 39.82s179.41591°	+17° 18′ 39.9″17.31108°	7.1′′	Poor	3 (U)	9.9′	10.3 ks
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: 4.0×10-4 ct s-1 (PSPC count-rate) Mean XRT rate converted to PSPC: 0.11 (+0.06, -0.05) ×10-1 ct s-1 Peak XRT rate converted to PSPC: 0.11 (+0.06, -0.05) ×10-1 ct s-1 Mean XRT flux: 4.4 (+2.6, -1.9) ×10-14 erg cm-1s-1 Peak XRT flux: 4.4 (+2.6, -1.9) ×10-14 erg cm-1s-1 Products: Light curve | Spectrum
12 [details]	11h 57m 02.09s179.25872°	+17° 33′ 22.7″17.55631°	7.8′′	Good	3 (U)	10.2′	10.3 ks
Mean XRT rate: 2.3 (+0.8, -0.6) ×10-3 ct s-1 Peak XRT rate: 2.87 (+1.08, -0.88) ×10-3 ct s-1 RASS PSPC 3-σ upper limit: 0.03 ct s-1 (PSPC count-rate) Mean XRT rate converted to PSPC: 3.32 (+1.11, -0.86) ×10-3 ct s-1 Peak XRT rate converted to PSPC: 4.1 (+1.5, -1.3) ×10-3 ct s-1 Mean XRT flux: 5.6 (+1.9, -1.5) ×10-14 erg cm-1s-1 Peak XRT flux: 6.9 (+2.6, -2.1) ×10-14 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.

Image

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Exposure map

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FITS exposure map.