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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"

32715 results found.

  1. GRB 250721A: Tiled Swift observations
  2. GRB 250721A: MAXI/GSC detection
  3. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  4. EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit
  5. GRB 250717B: COLIBRÍ optical upper limit
  6. GRB 250718B: Fermi GBM Final Localization Correction
  7. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  8. GRB 250717B: Swift ToO observations
  9. GRB 270713A: Kitab and AbAO Optical Observations
  10. GRB 250717B: Fermi GBM Observation
  11. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  12. Konus-Wind detection of GRB 250716A
  13. GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
  14. GRB 250716A: Swift ToO observations
  15. GRB 250714A: SVOM/GRM observation
  16. Fermi GRB 250716A: Global MASTER-Net observations report
  17. Fermi GRB 250715A: Global MASTER-Net observations report
  18. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  19. GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray observations
  20. GRB 250713A: Mephisto optical upper limits
  21. Fermi GRB 250714A: Global MASTER-Net observations report
  22. GRB 250713A: SVOM/VT optical upper limit
  23. GRB 250713A: NOT optical upper limits
  24. GRB 250713A: OHP/T193 upper limit
  25. GRB 250713A: SVOM/C-GFT upper limit
  26. GRB 250706B/C: 7DT Follow-up Observations
  27. GRB 250713A: EP-FXT counterpart detection
  28. EP250711a: COLIBRÍ continuous optical observations
  29. GRB 250706A: Swift-BAT refined analysis
  30. GRB 250702F: Swift-BAT refined analysis
  31. GRB 250628A: Swift-BAT refined analysis
  32. LIGO/Virgo/KAGRA S250712cd: Updated Sky localization
  33. GRB 250713A: JinShan optical upper limits
  34. EP250711a: Global MASTER-Net observations report
  35. GRB 250711A: DDOTI Optical Upper Limit
  36. LIGO/Virgo/KAGRA S250712cd: Identification of a GW compact binary merger candidate
  37. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate (duplicate submission)
  38. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate
  39. GRB 250711A: SVOM/GRM observation
  40. EP250711a: NOT optical counterpart candidate
  41. EP250711a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  42. Fermi GRB 250711A: Global MASTER-Net observations report
  43. EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  44. GRB 250704A: GRANDMA observations
  45. GRB 250704A: SVOM/ECLAIRs refined analysis
  46. LIGO/Virgo/KAGRA S250711q: Identification of a GW compact binary merger candidate
  47. GRB 250702B,D,E/EP250702A: JCMT sub-mm observations at 350 GHz
  48. GRB 250704B / EP250704a: 1.3 GHz MeerKAT Detection
  49. GRB 250702B,D,E / EP250702a: ALMA detection
  50. IceCube-250708A: No Candidates from WINTER
  51. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
  52. GRB 250702B,D,E / EP250702a: 10 GHz detection with the VLA
  53. IceCube-250708A: Upper limits from a search for additional neutrino events in IceCube
  54. IPN triangulation of GRB 250704B (short/hard, consistent with EP 250704a)
  55. GRB 250706B/C: Insight-HXMT detection
  56. EP/WXT 01709181970: GOTO observations confirm stellar variability
  57. EP250704a/GRB 250704B: 10 GHz VLA detection
  58. GRB250702 B,D,E / EP250702a: MOSFIRE imaging of the afterglow
  59. IceCube-250706A: No Candidates from WINTER
  60. IPN triangulation of GRB 250706C (consistent with the GRB 250706B)
  61. IceCube-250706A: No Candidates from the Zwicky Transient Facility
  62. GRB 250704B / EP250704a: VLA radio detection
  63. Fermi GRB 250708A: Global MASTER-Net observations report
  64. IceCube-250706A: Upper limits from a search for additional neutrino events in IceCube
  65. LIGO/Virgo/KAGRA S250705cb: Updated Sky localization
  66. LIGO/Virgo/KAGRA S250704ab: Updated Sky localization and EM Bright Classification
  67. LIGO/Virgo/KAGRA S250702n: Updated Sky localization
  68. LIGO/Virgo/KAGRA S250701bq: Updated Sky localization
  69. EP250704a/GRB250704B : HCT optical and NIR upper limits
  70. LIGO/Virgo/KAGRA S250701bp: Updated Sky localization
  71. GRB 250706B/C: Konus-Wind analysis of the prompt emission
  72. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  73. GRB 250704B: CALET Gamma-Ray Burst Monitor detection
  74. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  75. GRB 250702F: radio detection with the VLA
  76. GRB 250706B/C: VLT/X-shooter redshift z = 0.942
  77. IceCube-250706A: EP-FXT follow-up observations
  78. Fermi-LAT Gamma-ray Observations of IceCube-250706A
  79. GRB 250706B/C: Fermi-LAT detection
  80. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  81. EP250702a/GRB250702 B,D,E: GRANDMA Upper Limit
  82. GRB 250706B: Swift/UVOT Detection
  83. EP250702a/ GRB 250702B: NuSTAR X-ray Observations
  84. GRB 250706C: Konus-Wind detection of a very bright GRB ~1200 s before GRB 250706B
  85. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  86. GRB 250702F: GRANDMA observations
  87. GRB 250706B: refined SVOM/MXT data analysis
  88. GRB 250706A: Swift/UVOT Upper Limits
  89. GRB 250706B: REM optical observations
  90. GRB 250706A: REM optical/NIR observations
  91. EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
  92. IceCube-250416A: DDOTI Optical Upper Limit
  93. IceCube-250706A: COLIBRÍ optical upper limits
  94. Swift GRB 250706A: Global MASTER-Net observations report
  95. GRB 250706A: JinShan optical upper limits
  96. GRB 250706A: SAO RAS optical observations
  97. EP250704A: NOWT Detection
  98. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  99. GRB250706B: Swift-XRT counterpart detection
  100. GRB 250706B: iTelescope optical observations

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