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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"

45906 results found.

  1. GRB 250721A: Fermi GBM Final Localization
  2. GRB 250720B: Fermi GBM Final Localization Correction
  3. GRB 250720A: Fermi GBM Final Localization
  4. Fermi trigger No 774730635: Global MASTER-Net observations report
  5. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  6. Fermi Gamma-ray Burst Monitor trigger 774670514/250720094 is not a GRB
  7. EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit
  8. GRB 250717B: COLIBRÍ optical upper limit
  9. LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO
  10. GRB 250717B: Swift-XRT observations
  11. GRB 250718B: Fermi GBM Final Localization Correction
  12. GRB 250718B: Fermi GBM Final Real-time Localization
  13. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  14. Swift Trigger 1334535: a possible GRB 250718A
  15. Swift GRB250718.01: Global MASTER-Net observations report
  16. GRB 250717B: Swift ToO observations
  17. GRB 270713A: Kitab and AbAO Optical Observations
  18. GRB 250717B: Fermi GBM Observation
  19. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  20. Konus-Wind detection of GRB 250716A
  21. GRB 250716A: Swift-XRT afterglow detection
  22. GRB 250717B: Fermi GBM Final Real-time Localization
  23. GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
  24. GRB 250717A: Fermi GBM Final Real-time Localization
  25. GRB 250716A: Swift ToO observations
  26. GRB 250716A: GOTO tentative optical counterpart candidate
  27. GRB 250716A: Fermi GBM Observation
  28. GRB 250714A: SVOM/GRM observation
  29. Fermi GRB 250716A: Global MASTER-Net observations report
  30. GRB 250716A: Fermi GBM Final Real-time Localization
  31. Fermi GRB 250715A: Global MASTER-Net observations report
  32. GRB 250715A: Fermi GBM Final Real-time Localization
  33. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  34. GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray observations
  35. GRB 250713A: Mephisto optical upper limits
  36. Fermi GRB 250714A: Global MASTER-Net observations report
  37. GRB 250713A: SVOM/VT optical upper limit
  38. GRB 250713A: NOT optical upper limits
  39. GRB 250713A: OHP/T193 upper limit
  40. GRB 250713A: SVOM/C-GFT upper limit
  41. GRB 250714A: Fermi GBM Final Real-time Localization
  42. GRB 250706B/C: 7DT Follow-up Observations
  43. GRB 250713A: Swift-XRT observations
  44. GRB 250713A: EP-FXT counterpart detection
  45. EP250711a: COLIBRÍ continuous optical observations
  46. GRB 250706A: Swift-BAT refined analysis
  47. GRB 250702F: Swift-BAT refined analysis
  48. GRB 250628A: Swift-BAT refined analysis
  49. LIGO/Virgo/KAGRA S250712cd: Updated Sky localization
  50. GRB 250713A: JinShan optical upper limits
  51. GRB 250713A: SVOM detection of a long burst
  52. EP250711a: Global MASTER-Net observations report
  53. GRB 250711A: DDOTI Optical Upper Limit
  54. LIGO/Virgo/KAGRA S250712cd: Identification of a GW compact binary merger candidate
  55. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate (duplicate submission)
  56. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate
  57. GRB 250711A: SVOM/GRM observation
  58. EP250711a: NOT optical counterpart candidate
  59. EP250711a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  60. EP candidate (ID=08500000365): COLIBRÍ optical Upper limit
  61. Fermi GRB 250711A: Global MASTER-Net observations report
  62. EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  63. GRB 250704A: GRANDMA observations
  64. GRB 250711A: BALROG localization (Fermi Trigger 773937617 / GRB 250711611)
  65. GRB 250711A: Fermi GBM Final Real-time Localization
  66. GRB 250704A: SVOM/ECLAIRs refined analysis
  67. LIGO/Virgo/KAGRA S250711q: Identification of a GW compact binary merger candidate
  68. GRB 250702B,D,E/EP250702A: JCMT sub-mm observations at 350 GHz
  69. GRB 250704B / EP250704a: 1.3 GHz MeerKAT Detection
  70. GRB 250702B,D,E / EP250702a: ALMA detection
  71. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  72. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  73. IceCube-250708A: No Candidates from WINTER
  74. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
  75. GRB 250702B,D,E/EP250702A: MeerKAT radio observations at 1.28GHz
  76. GRB 250702B,D,E / EP250702a: 10 GHz detection with the VLA
  77. IceCube-250708A: Upper limits from a search for additional neutrino events in IceCube
  78. GRB 250709A: Fermi GBM Final Localization
  79. IPN triangulation of GRB 250704B (short/hard, consistent with EP 250704a)
  80. GRB 250706B/C: Insight-HXMT detection
  81. EP/WXT 01709181970: GOTO observations confirm stellar variability
  82. EP-WXT trigger 01709181970. confirmation of a stellar flare by BOOTES-6
  83. EP250704a/GRB 250704B: 10 GHz VLA detection
  84. The EP-WXT trigger 01709181970 is likely a flaring star
  85. GRB250702 B,D,E / EP250702a: MOSFIRE imaging of the afterglow
  86. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 4-Update Localization Volume
  87. IceCube-250706A: No Candidates from WINTER
  88. IPN triangulation of GRB 250706C (consistent with the GRB 250706B)
  89. IceCube-250706A: No Candidates from the Zwicky Transient Facility
  90. IceCube-250708A - IceCube observation of a high-energy neutrino candidate track-like event
  91. GRB 250704B / EP250704a: VLA radio detection
  92. Fermi GRB 250708A: Global MASTER-Net observations report
  93. IceCube-250708A: Global MASTER-Net observations report
  94. IceCube-250706A: Upper limits from a search for additional neutrino events in IceCube
  95. LIGO/Virgo/KAGRA S250705cb: Updated Sky localization
  96. LIGO/Virgo/KAGRA S250704ab: Updated Sky localization and EM Bright Classification
  97. LIGO/Virgo/KAGRA S250702n: Updated Sky localization
  98. LIGO/Virgo/KAGRA S250701bq: Updated Sky localization
  99. EP250704a/GRB250704B : HCT optical and NIR upper limits
  100. LIGO/Virgo/KAGRA S250701bp: Updated Sky localization

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