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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"

43898 results found.

  1. GRB 250716A: Swift ToO observations
  2. GRB 250716A: GOTO tentative optical counterpart candidate
  3. GRB 250716A: Fermi GBM Observation
  4. GRB 250714A: SVOM/GRM observation
  5. Fermi GRB 250716A: Global MASTER-Net observations report
  6. GRB 250716A: Fermi GBM Final Real-time Localization
  7. Fermi GRB 250715A: Global MASTER-Net observations report
  8. GRB 250715A: Fermi GBM Final Real-time Localization
  9. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  10. GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray observations
  11. GRB 250713A: Mephisto optical upper limits
  12. Fermi GRB 250714A: Global MASTER-Net observations report
  13. GRB 250713A: SVOM/VT optical upper limit
  14. GRB 250713A: NOT optical upper limits
  15. GRB 250713A: OHP/T193 upper limit
  16. GRB 250713A: SVOM/C-GFT upper limit
  17. GRB 250714A: Fermi GBM Final Real-time Localization
  18. GRB 250706B/C: 7DT Follow-up Observations
  19. GRB 250713A: Swift-XRT observations
  20. GRB 250713A: EP-FXT counterpart detection
  21. EP250711a: COLIBRÍ continuous optical observations
  22. GRB 250706A: Swift-BAT refined analysis
  23. GRB 250702F: Swift-BAT refined analysis
  24. GRB 250628A: Swift-BAT refined analysis
  25. LIGO/Virgo/KAGRA S250712cd: Updated Sky localization
  26. GRB 250713A: JinShan optical upper limits
  27. GRB 250713A: SVOM detection of a long burst
  28. EP250711a: Global MASTER-Net observations report
  29. GRB 250711A: DDOTI Optical Upper Limit
  30. LIGO/Virgo/KAGRA S250712cd: Identification of a GW compact binary merger candidate
  31. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate (duplicate submission)
  32. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate
  33. GRB 250711A: SVOM/GRM observation
  34. EP250711a: NOT optical counterpart candidate
  35. EP250711a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  36. EP candidate (ID=08500000365): COLIBRÍ optical Upper limit
  37. Fermi GRB 250711A: Global MASTER-Net observations report
  38. EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  39. GRB 250704A: GRANDMA observations
  40. GRB 250711A: BALROG localization (Fermi Trigger 773937617 / GRB 250711611)
  41. GRB 250711A: Fermi GBM Final Real-time Localization
  42. GRB 250704A: SVOM/ECLAIRs refined analysis
  43. LIGO/Virgo/KAGRA S250711q: Identification of a GW compact binary merger candidate
  44. GRB 250702B,D,E/EP250702A: JCMT sub-mm observations at 350 GHz
  45. GRB 250704B / EP250704a: 1.3 GHz MeerKAT Detection
  46. GRB 250702B,D,E / EP250702a: ALMA detection
  47. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  48. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  49. IceCube-250708A: No Candidates from WINTER
  50. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
  51. GRB 250702B,D,E/EP250702A: MeerKAT radio observations at 1.28GHz
  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. GRB 250709A: Fermi GBM Final Localization
  55. IPN triangulation of GRB 250704B (short/hard, consistent with EP 250704a)
  56. GRB 250706B/C: Insight-HXMT detection
  57. EP/WXT 01709181970: GOTO observations confirm stellar variability
  58. EP-WXT trigger 01709181970. confirmation of a stellar flare by BOOTES-6
  59. EP250704a/GRB 250704B: 10 GHz VLA detection
  60. The EP-WXT trigger 01709181970 is likely a flaring star
  61. GRB250702 B,D,E / EP250702a: MOSFIRE imaging of the afterglow
  62. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 4-Update Localization Volume
  63. IceCube-250706A: No Candidates from WINTER
  64. IPN triangulation of GRB 250706C (consistent with the GRB 250706B)
  65. IceCube-250706A: No Candidates from the Zwicky Transient Facility
  66. IceCube-250708A - IceCube observation of a high-energy neutrino candidate track-like event
  67. GRB 250704B / EP250704a: VLA radio detection
  68. Fermi GRB 250708A: Global MASTER-Net observations report
  69. IceCube-250708A: Global MASTER-Net observations report
  70. IceCube-250706A: Upper limits from a search for additional neutrino events in IceCube
  71. LIGO/Virgo/KAGRA S250705cb: Updated Sky localization
  72. LIGO/Virgo/KAGRA S250704ab: Updated Sky localization and EM Bright Classification
  73. LIGO/Virgo/KAGRA S250702n: Updated Sky localization
  74. LIGO/Virgo/KAGRA S250701bq: Updated Sky localization
  75. EP250704a/GRB250704B : HCT optical and NIR upper limits
  76. LIGO/Virgo/KAGRA S250701bp: Updated Sky localization
  77. GRB 250708A: Fermi GBM Final Real-time Localization
  78. GRB 250706B/C: Konus-Wind analysis of the prompt emission
  79. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  80. GRB 250704B: CALET Gamma-Ray Burst Monitor detection
  81. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  82. GRB 250702F: radio detection with the VLA
  83. GRB 250706B/C: VLT/X-shooter redshift z = 0.942
  84. IceCube-250706A: EP-FXT follow-up observations
  85. Fermi-LAT Gamma-ray Observations of IceCube-250706A
  86. GRB 250706B/C: Fermi-LAT detection
  87. IceCube-250706A: Global MASTER-Net observations report
  88. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  89. EP250702a/GRB250702 B,D,E: GRANDMA Upper Limit
  90. GRB 250706B: Swift/UVOT Detection
  91. EP250702a/ GRB 250702B: NuSTAR X-ray Observations
  92. GRB 250706C: Konus-Wind detection of a very bright GRB ~1200 s before GRB 250706B
  93. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  94. GRB 250702F: GRANDMA observations
  95. GRB 250706A: Swift-XRT refined Analysis
  96. GRB 250706B: refined SVOM/MXT data analysis
  97. GRB 250706B: REM optical observations
  98. GRB 250706A: REM optical/NIR observations
  99. EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
  100. IceCube-250416A: DDOTI Optical Upper Limit

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