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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').
Advanced Search

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.

Advanced Search Examples (click to copy):

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

32706 results found.

  1. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  2. Fermi GRB 251128A: Global MASTER-Net observations report
  3. GRB 251127A: Glowbug gamma-ray detection
  4. GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
  5. GRB 251126A: further SAO RAS optical observations
  6. GRB 250702B: detection of the compact radio counterpart 139 days after the burst
  7. GRB 251126A NUTTelA-TAO Early Measurements
  8. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  9. GRB251126A: MAO/AZT-22 optical observations
  10. GRB251126A: Continued optical observation from 1.3m DFOT
  11. GRB 251126A: Swift/UVOT Detection
  12. EP251124a: Pan-STARRS ri-band imaging and photometry
  13. GRB 251126A: Mondy and SAO RAS optical observations
  14. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  15. GRB 251126A: NOT optical observations
  16. GRB 251126A: 1.3m DFOT optical afterglow detection
  17. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  18. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  19. GRB 251125B: GECAM-B detection
  20. Fermi GRB 251127A: Global MASTER-Net observations report
  21. GRB 251126A: Kilonova-Catcher optical afterglow detection
  22. GRB 251126A: Asiago i-band detection
  23. GRB 251126A: Nanshan/HMT optical afterglow detection
  24. Swift GRB 251126A: Global MASTER-Net observations report
  25. GRB 251121A: Fermi GBM Observation
  26. GRB 251126A: GIT discovery of the likely optical afterglow
  27. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  28. EP251124b follow-up observation by EP-FXT
  29. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  30. EP251124b: NOT r- and z-band optical upper limits
  31. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  32. Fermi GRB 251125B: Global MASTER-Net observations report
  33. EP251124b: Global MASTER-Net observations report
  34. EP251124a: Xinglong GWAC-F60A optical observation
  35. EP251124a (EP-WXT trigger 01709248862) is triggered by the known source AWM 7
  36. Fermi GRB 251125A: Global MASTER-Net observations report
  37. EP251124a: NOT r- and z-band optical upper limits
  38. EP251124a: Global MASTER-Net observations report
  39. GRB 251124A: Fermi GBM Localization by automated pipeline
  40. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  41. EP251124a: Optical upper limit with Kinder observations
  42. EP251118A: 6 GHz VLA Detection
  43. Fermi GRB 251124a: Global MASTER-Net observations report
  44. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  45. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  46. EP251124a: GROWTH-India Telescope optical upper limits
  47. GRB 251116C: Swift-XRT confirmation of fading
  48. GRB 251122A/EP251122a: FTW optical and NIR observations
  49. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  50. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  51. EP251118A: 3.6m DOT optical afterglow detection
  52. GRB 251122A / EP251122a: EP-FXT counterpart detection
  53. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  54. GRB 251122A / EP251122a: WFST optical observations
  55. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  56. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  57. GRB 251122A / EP251122a: LCO optical upper limits
  58. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  59. EP251122a: Global MASTER-Net observations report
  60. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  61. GRB 251122A / EP251122a: SVOM detection of a long burst
  62. EP251118a: Continued Optical Detection with Kinder observations
  63. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  64. LIGO/Virgo/KAGRA S251112cm: SOAR spectroscopy of three TROVE TNS candidates
  65. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  66. GRB 251121A: Glowbug gamma-ray detection of a likely short burst
  67. EP251118a: Xinglong-2.16m optical observation
  68. GRB 251115A: Fermi GBM Observation
  69. EP251118A: 1.3m DFOT optical afterglow detection
  70. GRB 251118A: Swift/UVOT Detection
  71. EP251118a / GRB 251118C: SAO RAS optical observations
  72. GRB 251118A: Glowbug gamma-ray detection
  73. GRB 251118A: Fermi GBM Observation
  74. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  75. EP251118a: Optical detection with Kinder observations
  76. GRB 251118A: GECAM-B detection
  77. LIGO/Virgo/KAGRA S251112cm: SVOM/VT optical observations and preliminary results
  78. EP251118a / GRB 251118C: SVOM/VT optical observation
  79. GRB 251118A: NuSTAR detection of bright prompt emission
  80. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  81. GRB 251116C: NOT optical observations
  82. GRB 251118C: Glowbug gamma-ray detection of the fast X-ray transient EP251118A
  83. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  84. EP251118A / GRB 251118C : MASTER optical counterpart observations
  85. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  86. Konus-Wind detection of GRB 251118C (EP251118a)
  87. EP251118a: FTW optical and NIR observations
  88. GRB 251117A: Insight-HXMT/HE detection
  89. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  90. EP251118a: VLT near-infrared observation
  91. GRB 251116D: SVOM/GRM observation of a long GRB
  92. EP251118a: GOTO optical afterglow detection
  93. EP251118a: NOT spectroscopic redshift of z = 1.216
  94. EP251118a: Global MASTER-Net observations report
  95. EP251118a: preliminary result of EP-FXT follow-up observation
  96. GRB 251118A: Fermi-LAT detection
  97. EP251118a: NOT candidate optical counterpart
  98. GRB 251118A: Swift ToO observations
  99. EP251118a: Einstein Probe detected of a fast X-ray transient
  100. Fermi GRB 251118B: Global MASTER-Net observations report

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