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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').
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"

3105 results found.

  1. GRB 260926B: Fermi GBM Final Real-time Localization
  2. EP260924a: J-band upper limit by SYSU 80cm infrared telescope
  3. Fermi GRB 260923A: Global MASTER-Net observations report
  4. GRB 260918A: SVOM/ECLAIRs refined analysis
  5. GRB 260922A: Swift detection of a burst
  6. EP260920b: LCO observations
  7. EP Alert 260921.01: Global MASTER-Net observations report
  8. EP Alert 260919.40: Global MASTER-Net observations report
  9. Fermi GBM Sub-Threshold Detection of GRB 260918A
  10. EP Alert 260918.24: Global MASTER-Net observations report
  11. SVOM GRB260918.16: Global MASTER-Net observations report
  12. GRB 260918A: SVOM detection of a burst
  13. GRB 260917C: Fermi GBM Final Real-time Localization
  14. GRB 260917A: Fermi GBM Final Real-time Localization
  15. Fermi trigger No 811264269: Global MASTER-Net observations report
  16. GRB 260916A: MAXI/GSC detection
  17. EP Alert 260914.53: Global MASTER-Net observations report
  18. GRB 260909A: SVOM/ECLAIRs refined analysis
  19. EP Alert 260909.53: Global MASTER-Net observations report
  20. GRB 260909A: Mondy optical observations and afterglow candidate
  21. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  22. Fermi GRB 260907A: Global MASTER-Net observations report
  23. EP260901a: Global MASTER-Net observations report
  24. IceCube-260827A: No transient candidates from the Zwicky Transient Facility
  25. GRB 260825A: SVOM/GRM observation of a long burst
  26. GRB 260818B: Further EP-FXT observation
  27. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  28. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  29. IceCube Alert 260825A: Global MASTER-Net observations report
  30. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  31. EP260806a: SAO RAS multicolor optical observations
  32. GRB 260813A: Fermi GBM Final Real-time Localization
  33. GRB 260808B: SAO RAS optical observations
  34. GRB 260809A: NOT optical observations
  35. GRB 260809A: SVOM/VT optical counterpart
  36. IceCube-260805A: One candidate from the Zwicky Transient Facility
  37. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  38. Fermi GRB 260805A: Global MASTER-Net observations report
  39. Fermi GRB 260802B: Global MASTER-Net observations report
  40. The EP-WXT trigger 01709277130 (EP260729a): refined EP-WXT analysis and association with a flaring star
  41. EP260729a: Einstein Probe detection of an X-ray transient
  42. GRB 260726A: SVOM/VT optical candidate
  43. GRB 260726A: SVOM ECLAIRs improved position and MXT possible detection of a counterpart
  44. GRB 260727A: GOTO early optical upper limit
  45. Fermi GRB 260726A: Global MASTER-Net observations report
  46. EP260723a: further EP-FXT follow-up observation
  47. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  48. GRB 260718A : GRANDMA and KNC upper limits
  49. IceCube-260712A: No candidates with the Zwicky Transient Facility (ZTF)
  50. GRB 260714B: Fermi GBM Detection
  51. IceCube-260708A: One candidate from the Zwicky Transient Facility
  52. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  53. IceCube-260704A: No candidates from the Zwicky Transient Facility
  54. IPN triangulation of GRB 260627A
  55. Fermi GRB 260703A: Global MASTER-Net observations report
  56. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  57. Fermi trigger No 804552016: Global MASTER-Net observations report
  58. Konus-Wind detection of GRB 260623B / EP260623a
  59. EP260618a: EP-FXT follow-up observation
  60. GRB 260616C: GECAM-B observation of a burst
  61. GRB 260617A: Fermi GBM Detection
  62. GRB260616C: MAXI/GSC detection
  63. GRB 260614B: SVOM detection of a burst
  64. IceCube-260610A: No candidates from the Zwicky Transient Facility
  65. EP260610b: SVOM/VT optical confirmation with blue color
  66. EP260610a: SVOM/VT optical upper limits
  67. GRB 260608C: Fermi GBM Final Real-time Localization
  68. GRB 260607B: Fermi GBM Observation
  69. GRB 260604C: LAST detection of optical counterpart candidate
  70. EP260602a: EP-FXT follow-up observation
  71. EP260601a/GRB 260601B: EP-FXT follow-up observation
  72. Fermi GRB 260602B: Global MASTER-Net observations report
  73. Fermi GRB 260602B: Global MASTER-Net observations report
  74. GRB 260601A: Fermi GBM Observation
  75. Fermi trigger No 801900520: Global MASTER-Net observations report
  76. GRB 260531A: MAXI/GSC detection
  77. EP260527a/GRB 260527A: further FTW optical and NIR observations
  78. GRB 260527A / EP260527a: VLA radio detection
  79. GRB 260523A: Fermi GBM Final Real-time Localization
  80. Fermi GRB 260516C: Global MASTER-Net observations report
  81. GRB 260516B: Fermi GBM Final Real-time Localization
  82. SVOM GRB 260515A: Global MASTER-Net observations report
  83. SVOM GRB 260515A: MASTER OT J151044.43+243321.7 optical counterpart detection
  84. IceCube-260504A: No Candidate Transients from the Zwicky Transient Facility
  85. EP260514a: Global MASTER-Net observations report
  86. GRB 260511B: Mephisto multi-band optical followup
  87. GRB 260511B: LCO optical counterpart detection
  88. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
  89. EP260509a: LCO optical upper limits
  90. GRB 260510C: SVOM/VT optical upper limits
  91. SVOM GRB 260509A: MASTER-OAFA optical observation
  92. GRB 260509A: SVOM/VT optical candidate with VHF data
  93. GRB 260509A: GOTO optical counterpart candidate
  94. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  95. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  96. EP260507a: Kinder optical counterpart candidate
  97. EP260507a: LCO optical counterpart
  98. EP260507a: Einstein Probe detection of an X-ray transient
  99. Fermi GRB 260506A: Global MASTER-Net observations report
  100. GRB 260430B: AstroSat CZTI detection of a long burst

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