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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
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To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

20414 results found.

  1. EP250828a: Einstein Probe detection of an X-ray transient
  2. EP250827a: Preliminary analysis of the EP-WXT and EP-FXT observations
  3. GRID detection of GRB 250824A
  4. LIGO/Virgo/KAGRA S250827fo: Identification of a GW compact binary merger candidate
  5. EP250827a: confirmation of optical rebrightening with LCO
  6. GRB 250826A: SVOM/GRM observation
  7. EP250827A: An optical rebrightening was detected by LCO.
  8. EP250827a: TRT optical observations
  9. EP250827a: Einstein Probe detection of an X-ray transient
  10. LIGO/Virgo/KAGRA S250827l: Identification of a GW compact binary merger candidate
  11. GRB 250806A: HiPERCAM/GTC limits on a possible supernova
  12. LIGO/Virgo/KAGRA S250818k: SAO RAS BTA z-band observations of AT2025ulz
  13. Fermi GRB 250824B: Global MASTER-Net observations report
  14. LIGO/Virgo/KAGRA S250818k: VLA upper limits on AT2025ulz
  15. LIGO/Virgo/KAGRA S250818k: Pan-STARRS imaging confirms re-brightening of SN2025ulz
  16. LIGO/Virgo/KAGRA S250818k: MASTER predicovery limits of the AT2025ulz/ZTF25abjmnps KN candidate
  17. LIGO/Virgo/KAGRA S250818k: ENGRAVE observations of SN 2025ulz as a type II supernova
  18. EP250821a: MeerKAT radio counterpart
  19. GRB 250823A: COLIBRÍ optical observations
  20. GRB 250823A: SVOM/VT optical observation
  21. GRB 250823A: Swift/UVOT Detection
  22. LIGO/Virgo/KAGRA S250818k: COLIBRÍ confirmation of rebrightening of AT2025ulz
  23. GRB 250823A: Enhanced Swift-XRT position
  24. GRB 250823A: LCOGT Optical Detection
  25. GRB 250823A: Swift detection of a burst
  26. LIGO/Virgo/KAGRA S250818k: HST nIR detection of AT 2025ulz
  27. LIGO/Virgo/KAGRA S250818k: GTC/OSIRIS Optical Detection of AT2025ulz
  28. LIGO/Virgo/KAGRA S250818k: 3 GHz MeerKAT observations of AT2025ulz
  29. GRB 250806A: Gemini observations of host galaxy candidate
  30. GRB 250821A: Kilonova-Catcher optical upper limits
  31. GRB 250812A: SVOM/ECLAIRs refined analysis
  32. LIGO/Virgo/KAGRA S250818k: Pan-STARRS coverage of the skymap and candidate counterparts
  33. EP250821a: VLT X-shooter spectroscopic redshift z = 0.577
  34. GRB 250821A: VLT/FORS2 Optical Observation
  35. GRB 250821B: SVOM/GRM observation
  36. EP250821a: SVOM/VT optical observation
  37. GRB 250821A: NOT z-band upper limit
  38. GRB 250821A: KAIT optical upper limit
  39. GRB 250821A: Swift-XRT refined Analysis
  40. GRB 250821A: Enhanced Swift-XRT position
  41. GRB 250821A: Swift/UVOT Upper Limits
  42. LIGO/Virgo/KAGRA S250818k: GOTO counterpart search and upper limits
  43. EP250821a: Preliminary analysis of the EP-WXT and EP-FXT observations
  44. GRB 250821A: LCOGT Optical Upper Limits
  45. GRB 250814A: CMO SAI and SAO RAS izJ observations.
  46. LIGO/Virgo/KAGRA S250818k: 10 GHz VLA observations of AT2025ulz
  47. GRB 250821A: Swift detection of a burst
  48. LIGO/Virgo/KAGRA S250818k: WFST pre-discovery limits and follow-up observations of AT 2025ulz
  49. EP250821a: Einstein Probe detection of an X-ray transient
  50. GRB 250819A: SVOM/GRM observation of a possible “long” duration type I burst
  51. LIGO/Virgo/KAGRA S250818k: WINTER J-band observations of AT 2025ulz
  52. GRB 250818B: 10 GHz VLA detection
  53. LIGO/Virgo/KAGRA S250818k: Pan-STARRS grizy-band imaging and photometry of AT2025ulz
  54. LIGO/Virgo/KAGRA S250818k: ATLAS pre-discovery limits for AT2025ulz
  55. GRB 250814A: Swift/UVOT Upper Limits
  56. GRB 250813B: Swift/UVOT Upper Limit
  57. IPN triangulation of GRB 250816A (short)
  58. IPN triangulation of GRB 250814C (short)
  59. IPN triangulation of GRB 250804B (short)
  60. GRB 250818B: Kilonova-Catcher optical afterglow detection
  61. LIGO/Virgo/KAGRA S250818k: Pan-STARRS pre-detection limits for AT2025ulz
  62. LIGO/Virgo/KAGRA S250818k: Properties of the low-significance GW compact binary merger candidate potentially associated with AT 2025ulz
  63. GRB 250818B: Swift/UVOT Detection
  64. GRB 250818B: SAO RAS optical observations
  65. GRB 250818B: KAIT optical observations
  66. GRB 250818A: Swift/UVOT Upper Limits
  67. GRB 250818A: Enhanced Swift-XRT position
  68. GRB 250813B: SVOM/ECLAIRs refined analysis
  69. LIGO/Virgo/KAGRA S250818k: Coverage and upper limits from MAXI/GSC observations
  70. GRB 250814A: Further GRAWITA TNG NIR observations
  71. LIGO/Virgo/KAGRA S250818t: Identification of a GW compact binary merger candidate
  72. GRB 250818A: Swift detection of a burst
  73. GRB 250816A: SVOM/GRM observation of a short burst
  74. GRB 250813B: Liverpool Telescope optical upper limits
  75. GRB 250814A: Further COLIBRÍ optical upper limit
  76. GRB 250814A: detection of the afterglow candidate with Liverpool Telescope
  77. GRB 250814A: GRAWITA TNG NIR observations
  78. GRB 250814A: Mondy optical observations of the candidate counterpart to LVK S250814bg
  79. GRB 250813B: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  80. GRB250814A: TRT optical upper limits
  81. GRB 250814B: SVOM/GRM observation
  82. LIGO/Virgo/KAGRA S250813k: Swift XRT observations, 2 X-ray sources
  83. GRB 250814A: P200/WIRC observations of the afterglow candidate
  84. GRB 250814A: possible optical afterglow candidate at Spanish observatories
  85. GRB 250814A: KAIT optical upper limit
  86. GRB 250814A: Swift-XRT refined Analysis
  87. GRB 250814A: Possible afterglow candidate from P200/WIRC
  88. GRB 250813B: Fermi GBM Observation
  89. GRB 250814A: Optical observations with MDM Hiltner 2.4m telescope
  90. GRB 250814A: J-band upper limit from WINTER
  91. IceCube-250813A: Upper limits from a search for additional neutrino events in IceCube
  92. GRB 250813B: NOT observations of the optical afterglow
  93. GRB 250814A: COLIBRÍ optical upper limit
  94. GRB 250813A: AstroSat CZTI detection
  95. LIGO/Virgo/KAGRA S250814bg: Identification of a GW compact binary merger candidate possibly associated with GRB 250814A detected by Fermi GBM and Swift BAT
  96. GRB 250813B: VLT X-shooter spectroscopic redshift z = 1.752
  97. GRB 250814A: DDOTI Optical Upper Limit
  98. Fermi-LAT Gamma-ray Observations of IceCube-250813A
  99. GRB 250814A: Swift detection of a burst coincident with a subthreshold GW trigger
  100. GRB 250813B: SVOM/COLIBRÍ (FM-GFT) optical observations

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