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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"

43047 results found.

  1. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  2. EP250702a/GRB250702 B,D,E: uGMRT Radio detection in 1.26 GHz
  3. SVOM J195836+32283/sb25072103: Second VT observation
  4. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  5. GRB 250723B: Fermi GBM Final Real-time Localization
  6. GRB 250721A: Fermi GBM Observation
  7. GRB 250723A: Fermi GBM Final Real-time Localization
  8. SVOM J195836+32283/sb25072103: Swift XRT/UVOT upper limits
  9. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  10. GRB 250721A: Swift-XRT observations
  11. GRB 250722A: Fermi GBM Final Real-time Localization
  12. GRB 250713A : SVOM/ECLAIRs refined analysis
  13. GRB 250717B: SVOM/GRM observation
  14. LIGO/Virgo/KAGRA S250711q: Updated Sky localization
  15. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  16. GRB 250721A: Tiled Swift observations
  17. GRB 250721A: MAXI/GSC detection
  18. GRB 250721A: Fermi GBM Final Localization
  19. GRB 250720B: Fermi GBM Final Localization Correction
  20. GRB 250720A: Fermi GBM Final Localization
  21. Fermi trigger No 774730635: Global MASTER-Net observations report
  22. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  23. EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit
  24. GRB 250717B: COLIBRÍ optical upper limit
  25. LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO
  26. GRB 250717B: Swift-XRT observations
  27. GRB 250718B: Fermi GBM Final Localization Correction
  28. GRB 250718B: Fermi GBM Final Real-time Localization
  29. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  30. Swift Trigger 1334535: a possible GRB 250718A
  31. Swift GRB250718.01: Global MASTER-Net observations report
  32. GRB 250717B: Swift ToO observations
  33. GRB 270713A: Kitab and AbAO Optical Observations
  34. GRB 250717B: Fermi GBM Observation
  35. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  36. Konus-Wind detection of GRB 250716A
  37. GRB 250716A: Swift-XRT afterglow detection
  38. GRB 250717B: Fermi GBM Final Real-time Localization
  39. GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
  40. GRB 250717A: Fermi GBM Final Real-time Localization
  41. GRB 250716A: Swift ToO observations
  42. GRB 250716A: GOTO tentative optical counterpart candidate
  43. GRB 250716A: Fermi GBM Observation
  44. GRB 250714A: SVOM/GRM observation
  45. Fermi GRB 250716A: Global MASTER-Net observations report
  46. GRB 250716A: Fermi GBM Final Real-time Localization
  47. Fermi GRB 250715A: Global MASTER-Net observations report
  48. GRB 250715A: Fermi GBM Final Real-time Localization
  49. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  50. GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray observations
  51. GRB 250713A: Mephisto optical upper limits
  52. Fermi GRB 250714A: Global MASTER-Net observations report
  53. GRB 250713A: SVOM/VT optical upper limit
  54. GRB 250713A: NOT optical upper limits
  55. GRB 250713A: OHP/T193 upper limit
  56. GRB 250713A: SVOM/C-GFT upper limit
  57. GRB 250714A: Fermi GBM Final Real-time Localization
  58. GRB 250706B/C: 7DT Follow-up Observations
  59. GRB 250713A: Swift-XRT observations
  60. GRB 250713A: EP-FXT counterpart detection
  61. EP250711a: COLIBRÍ continuous optical observations
  62. GRB 250706A: Swift-BAT refined analysis
  63. GRB 250702F: Swift-BAT refined analysis
  64. GRB 250628A: Swift-BAT refined analysis
  65. LIGO/Virgo/KAGRA S250712cd: Updated Sky localization
  66. GRB 250713A: JinShan optical upper limits
  67. GRB 250713A: SVOM detection of a long burst
  68. EP250711a: Global MASTER-Net observations report
  69. GRB 250711A: DDOTI Optical Upper Limit
  70. LIGO/Virgo/KAGRA S250712cd: Identification of a GW compact binary merger candidate
  71. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate (duplicate submission)
  72. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate
  73. GRB 250711A: SVOM/GRM observation
  74. EP250711a: NOT optical counterpart candidate
  75. EP250711a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  76. EP candidate (ID=08500000365): COLIBRÍ optical Upper limit
  77. Fermi GRB 250711A: Global MASTER-Net observations report
  78. EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  79. GRB 250704A: GRANDMA observations
  80. GRB 250711A: BALROG localization (Fermi Trigger 773937617 / GRB 250711611)
  81. GRB 250711A: Fermi GBM Final Real-time Localization
  82. GRB 250704A: SVOM/ECLAIRs refined analysis
  83. LIGO/Virgo/KAGRA S250711q: Identification of a GW compact binary merger candidate
  84. GRB 250702B,D,E/EP250702A: JCMT sub-mm observations at 350 GHz
  85. GRB 250704B / EP250704a: 1.3 GHz MeerKAT Detection
  86. GRB 250702B,D,E / EP250702a: ALMA detection
  87. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  88. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  89. IceCube-250708A: No Candidates from WINTER
  90. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
  91. GRB 250702B,D,E/EP250702A: MeerKAT radio observations at 1.28GHz
  92. GRB 250702B,D,E / EP250702a: 10 GHz detection with the VLA
  93. IceCube-250708A: Upper limits from a search for additional neutrino events in IceCube
  94. GRB 250709A: Fermi GBM Final Localization
  95. IPN triangulation of GRB 250704B (short/hard, consistent with EP 250704a)
  96. GRB 250706B/C: Insight-HXMT detection
  97. EP/WXT 01709181970: GOTO observations confirm stellar variability
  98. EP-WXT trigger 01709181970. confirmation of a stellar flare by BOOTES-6
  99. The EP-WXT trigger 01709181970 is likely a flaring star
  100. GRB250702 B,D,E / EP250702a: MOSFIRE imaging of the afterglow

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