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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

28043 results found.

  1. EP251124b: EP-WXT detection of a fast X-ray transient
  2. EP251124a: Xinglong GWAC-F60A optical observation
  3. Fermi GRB 251125A: Global MASTER-Net observations report
  4. EP251124a: NOT r- and z-band optical upper limits
  5. EP251124a: Global MASTER-Net observations report
  6. EP251124a: Swift-XRT observations
  7. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  8. EP251124a: Optical upper limit with Kinder observations
  9. Fermi GRB 251124a: Global MASTER-Net observations report
  10. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  11. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  12. EP251124a: GROWTH-India Telescope optical upper limits
  13. EP251124a: Einstein Probe detection of an X-ray transient
  14. GRB 251116C: Swift-XRT confirmation of fading
  15. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  16. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  17. EP251118A: 3.6m DOT optical afterglow detection
  18. GRB 251122A / EP251122a: EP-FXT counterpart detection
  19. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  20. GRB 251122A / EP251122a: WFST optical observations
  21. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  22. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  23. GRB 251122A / EP251122a: LCO optical upper limits
  24. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  25. EP251122a: Global MASTER-Net observations report
  26. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  27. GRB 251122A / EP251122a: SVOM detection of a long burst
  28. EP251122a: Einstein Probe detection of an X-ray transient
  29. EP251118a: Continued Optical Detection with Kinder observations
  30. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  31. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  32. GRB 251121A: Glowbug gamma-ray detection of a likely short burst
  33. EP251118a: Xinglong-2.16m optical observation
  34. GRB 251115A: Fermi GBM Observation
  35. Fermi trigger No 785388351: Global MASTER-Net observations report
  36. EP251118A: 1.3m DFOT optical afterglow detection
  37. GRB 251118A: Swift/UVOT Detection
  38. EP251118a / GRB 251118C: SAO RAS optical observations
  39. GRB 251118A: Glowbug gamma-ray detection
  40. GRB 251118A: Fermi GBM Observation
  41. GRB 251118A: Swift-XRT afterglow detection
  42. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  43. EP251118a: Optical detection with Kinder observations
  44. LIGO/Virgo/KAGRA S251112cm: SVOM/VT optical observations and preliminary results
  45. GRB 251118A: NuSTAR detection of bright prompt emission
  46. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  47. GRB 251116C: NOT optical observations
  48. GRB 251118C: Glowbug gamma-ray detection of the fast X-ray transient EP251118A
  49. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  50. GRB 251117A: Swift-XRT observations
  51. EP251118A / GRB 251118C : MASTER optical counterpart observations
  52. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  53. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  54. EP251118a: VLT near-infrared observation
  55. GRB 251116D: SVOM/GRM observation of a long GRB
  56. GRB 251119A: SVOM detection of a possible burst
  57. EP251118a: Global MASTER-Net observations report
  58. LAT GRB251118.86: Global MASTER-Net observations report
  59. EP251118a: NOT candidate optical counterpart
  60. EP251118a: Einstein Probe detected of a fast X-ray transient
  61. Fermi GRB 251118B: Global MASTER-Net observations report
  62. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  63. GRB 251118A: BALROG localization (Fermi Trigger 785190695 / GRB 251118855)
  64. GRB 251117A: AstroSat CZTI detection
  65. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  66. LIGO/Virgo/KAGRA S251117dq: Updated Sky localization
  67. GRB 251115A: Swift-XRT observations
  68. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  69. GRB 251117A: SVOM/GRM observation of a short burst
  70. LAT GRB251117.51: Global MASTER-Net observations report
  71. LIGO/Virgo/KAGRA S251117dq: Identification of a GW compact binary merger candidate
  72. LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations
  73. LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
  74. GRB 251116C: Swift-XRT observations
  75. LIGO/Virgo/KAGRA S251116en: Updated Sky localization
  76. GRB 251116D: Glowbug gamma-ray detection
  77. EP251023a: Assy AZT-20 optical observations
  78. EP251023a: UAFO and AbAO optical observations
  79. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  80. GRB 251116C: SVOM/VT optical upper limit
  81. GRB 251025B: further Mondy optical observations
  82. GRB 251111A: Mondy optical upper limit
  83. GRB 251116B: EP-FXT follow-up observation
  84. LIGO/Virgo/KAGRA S251116en: Identification of a GW compact binary merger candidate
  85. LIGO/Virgo/KAGRA S251112cm: Observations with the NSF-DOE Vera C. Rubin Observatory
  86. GRB 251116B: LCO optical upper limits
  87. GRB 251116C: LCO optical upper limits
  88. SVOM GRB251116C: Global MASTER-Net observations report
  89. GRB 251116B: SVOM detection of a burst
  90. IceCube-Cascade 251112A: Upper limits from a search for additional neutrino events in IceCube
  91. LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap
  92. GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis
  93. Fermi GRB 251115A: Global MASTER-Net observations report
  94. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 4-Update Localization Volume
  95. LIGO/Virgo/KAGRA S251112cm: DECam GW-MMADS candidates
  96. LIGO/Virgo/KAGRA S251112cm: Updated Sky localization and false alarm rate estimate
  97. GRB 251113A: Glowbug gamma-ray detection
  98. GRB 251112A: Swift-BAT refined analysis
  99. Fermi trigger No 784717756: Global MASTER-Net observations report
  100. LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap

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