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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"

30654 results found.

  1. EP240708a: KAIT optical upper limit
  2. Fermi GRB 240710A: Global MASTER-Net observations report
  3. EP240708a: NOT optical observations
  4. EP240708a: SVOM/C-GFT optical upper limit
  5. EP240708a: X-ray follow-up observations with EP/FXT and Swift/XRT
  6. EP240708a: Optical upper limits with Kinder observations
  7. LIGO/Virgo S240615dg: Swift XRT observations, 28 futher X-ray sources
  8. EP240703b: GSP optical upper limit
  9. EP240703b: TRT optical upper limits
  10. EP240703a: TRT further optical observation
  11. EP240702a: TRT optical upper limits
  12. Konus-Wind detection of GRB 240627A
  13. LIGO/Virgo/KAGRA S240705at: Updated Sky localization
  14. EP240703a and EP240703b: Swift/XRT upper limits
  15. LIGO/Virgo/KAGRA S240705at: Identification of a GW compact binary merger candidate
  16. EP240703a: KAIT optical upper limit
  17. EP240703a: BTA observations
  18. EP240703c: Kinder optical follow-up and Swift XRT observations
  19. EP240703a: Liverpool Telescope optical follow-up observations
  20. EP240703a/GRB 240703A: TRT optical candidate likely not real
  21. EP240703a: Kinder optical follow-up observations
  22. LIGO/Virgo/KAGRA S240703ad: Updated Sky localization
  23. LIGO/Virgo/KAGRA S240703ad: Identification of a GW compact binary merger candidate
  24. EP240703a/GRB 240703A: TRT and JinShan decaying optical afterglow candidate
  25. IPN triangulation of GRB 240627A
  26. GRB 240619A: Host galaxy redshift from VLT/X-shooter
  27. LIGO/Virgo/KAGRA S240422ed: Updated significance estimate
  28. The first three GRBs detected by SVOM: X-ray Upper Limits from EP-WXT
  29. Konus-Wind detection of GRB 240703A (a counterpart of EP240703a)
  30. EP240702a: Swift/XRT upper limit
  31. EP240702a: GSP optical upper limit
  32. Fermi GRB 240702A: Global MASTER-Net observations report
  33. GRB 240627A: CALET Gamma-Ray Burst Monitor detection
  34. LIGO/Virgo/KAGRA S240630t: Updated Sky localization
  35. LIGO/Virgo/KAGRA S240629by: Updated Sky localization
  36. LIGO/Virgo/KAGRA S240630t: Identification of a GW compact binary merger candidate
  37. LIGO/Virgo/KAGRA S240629by: Upper limits from Fermi-GBM Observations
  38. LIGO/Virgo/KAGRA S240629by: Coverage and upper limits from MAXI/GSC observations
  39. Fermi GRB 240629A: Global MASTER-Net observations report
  40. Fermi Gamma-ray Burst Monitor trigger 741288821/240628732 is not a GRB
  41. LIGO/Virgo/KAGRA S240629by: Identification of a GW compact binary merger candidate
  42. IPN triangulation of GRB 240619C
  43. GRB 240627A: NuSTAR Detection of the long GRB
  44. GRB 240615A: SAI CMO J- band observations
  45. EP240626a: Montarrenti Observatory optical upper limit
  46. LIGO/Virgo/KAGRA S240627by: Identification of a GW compact binary merger candidate
  47. EP240625a: GRANDMA Optical Upper Limits
  48. EP240626a: EP-FXT detection of the X-ray emission
  49. GRB 240624A: Swift-BAT refined analysis
  50. Konus-Wind detection of GRB 240619A
  51. Fermi GRB 240625B: Global MASTER-Net observations report
  52. GRB 240624B: CALET Gamma-Ray Burst Monitor detection
  53. GRB 240625A: Fermi GBM Observation
  54. EP240625a: NOT optical counterpart candidate
  55. EP240625a: EP-FXT detection of the X-ray emission
  56. GRB 240624B: GRBAlpha detection
  57. GRB240624A: Fermi GBM Observation
  58. Swift GRB 240624A: Global MASTER-Net observations report
  59. GRB240615A: Gemini-North observations of the BAT and XRT positions
  60. Fermi GRB 240624A: Global MASTER-Net observations report
  61. GRB240615A: Gemini-North observations of the BAT and XRT positions
  62. GRB 240619A: detection of a radio counterpart with AMI-LA
  63. EP240618a: NOT further optical observations
  64. GRB 240619A: J-band detection with WINTER (duplicate submission of GCN 36739)
  65. GRB 240619A: J-band detection with WINTER
  66. LIGO/Virgo/KAGRA S240622h: Updated Sky localization and Source Classification
  67. EP240618a: NOT optical counterpart candidate
  68. LIGO/Virgo/KAGRA S240621em: Updated Sky localization and Source Classification
  69. GRB 240529A: JinShan optical observations
  70. LIGO/Virgo/KAGRA S240621dy: Updated Sky localization and Source Classification
  71. LIGO/Virgo/KAGRA S240621eb: Updated Sky localization and Source Classification
  72. EP240618a: GSP optical upper limit
  73. LIGO/Virgo/KAGRA S240622h: Identification of a GW compact binary merger candidate
  74. LIGO/Virgo/KAGRA S240621em: Identification of a GW compact binary merger candidate
  75. LIGO/Virgo/KAGRA S240621eb: Identification of a GW compact binary merger candidate
  76. LIGO/Virgo/KAGRA S240621dy: Identification of a GW compact binary merger candidate
  77. IPN triangulation of GRB 240615A (short)
  78. X-ray transient EP240618a: Fermi/GBM non-detection
  79. GRB 240619A: GRBAlpha detection
  80. EP240618a: Swift/XRT upper limit
  81. EP240617a: tentative Swift/XRT detection of the afterglow
  82. GRB 240619A: Swift-XRT probable afterglow detection
  83. GRB 240619A: Swift ToO observations
  84. GRB 240619A: CALET Gamma-Ray Burst Monitor detection
  85. GRB 240619C: NuSTAR automated detection of the GRB
  86. GRB 240619A: Fermi GBM Observation
  87. Fermi GBM Sub-Threshold Detection of GRB 240619C
  88. GRB 240619A: GOTO candidate optical afterglow
  89. EP240618a: Abastumani optical observationsEP240618a
  90. GRB 240615A: NOT optical observations
  91. EP240618a: GRANDMA Optical Upper Limits
  92. EP240618a: TRT optical upper limit
  93. Fermi GRB 240619A: Global MASTER-Net observations report
  94. EP240617a: STEP/T80S optical limits
  95. GRB 240615A: possible transient detection from Wendelstein observations
  96. LIGO/Virgo S240615dg: GRANDMA/FRAM-CTA-N Observations
  97. LIGO/Virgo/KAGRA S240615dg: Updated Sky localization
  98. LIGO/Virgo/KAGRA S240618ah: Updated Sky localization
  99. EP240618a: OHP/T193 MISTRAL i' and Y band upper limits
  100. GRB240615A: 1.3m DFOT optical upper limit

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