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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"

15980 results found.

  1. GRB 260925A: COLIBRÍ optical upper limits
  2. GRB 260925A: FRAM-Auger optical limit
  3. GRB 260924A: Ondrejov D50 optical afterglow detection
  4. GRB 260924A: SVOM/GRM observation
  5. GRB 260924A: 2.2m CAHA spectroscopic redshift z = 3.51
  6. GRB 260924A: J-band observations by the SYSU 80 cm infrared telescope
  7. GRB 260924A: GROWTH-India Telescope optical observations
  8. GRB 260921A: SVOM/GRM observation
  9. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  10. GRB 260924A: Fermi GRB Observation
  11. GRB 260920A: SVOM/GRM observation
  12. GRB 260924A: NOT optical counterpart confirmation
  13. GRB 260924A: detection of a bright optical afterglow by the 1.5m OSN telescope
  14. GRB 260922A: Ondrejov D50 optical limit
  15. GRB 260922A: J-band upper limit with WINTER
  16. GRB 260922A: Swift/UVOT Upper Limits
  17. GRB 260922A: COLIBRÍ Optical Counterpart Candidate (correction to GCN 45698)
  18. GRB 260922A: COLIBRÍ optical upper limits
  19. GRB 260922A: SVOM/C-GFT optical upper limit
  20. GRB 260921A: Fermi GBM Observation
  21. EP260920b: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  22. Swift GRB 260921A: MASTER OT J094129.58+025052.5 possible optical counterpart detection with host galaxy (z=1.3)
  23. EP260920b: VLT/X-shooter spectroscopic redshift z = 3.582
  24. EP260920b: SVOM/VT optical observation
  25. EP260920b: COLIBRÍ optical observations
  26. EP260920b: LCO optical counterpart detection
  27. EP260920a: NOT early time optical upper limits
  28. EP260920a: NOT optical upper limits
  29. EP260920a: SVOM/VT optical upper limits
  30. EP260920a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  31. EP260920a: COLIBRÍ optical upper limits
  32. EP260920a: Update of the LCO optical counterpart candidate
  33. EP260920a: LCO optical counterpart candidate
  34. GRB 260915A: VLT optical and near-infrared upper limits
  35. EP260917a: SVOM/VT optical upper limits
  36. GRB 260918A: SVOM/C-GFT optical upper limits
  37. GRB 260918A: SVOM/VT optical upper limits
  38. GRB 260917B: Mondy optical upper limit
  39. GRB 260917B: EP-FXT follow-up observation
  40. EP260917a: COLIBRÍ optical upper limits
  41. GRB 260918A: LCO optical upper limits
  42. GRB 260918A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  43. GRB 260917B: FRAM-Auger optical limits
  44. GRB 260917B: WINTER J-band observations
  45. GRB 260917B: SVOM/VT optical observations
  46. GRB 260917B: LCO optical observation
  47. GRB 260917B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  48. GRB 260914A: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  49. GRB 260914A: Mondy and TShAO optical observations
  50. GRB 260915A: SVOM/C-GFT optical upper limits
  51. GRB 260915A: EP-FXT follow-up observation
  52. GRB 260915A: SVOM/VT refined early optical upper limits
  53. GRB 260915A: REM optical/NIR observations
  54. GRB 260914A: REM optical/NIR observations
  55. GRB 260914A: VLT/X-shooter observations and redshift confirmation
  56. GRB 260915A: SVOM/VT optical upper limits
  57. GRB 260915A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  58. GRB 260914A: VLT/X-shooter spectroscopic redshift z = 0.778
  59. GRB 260915A: 10.4m GTC deep optical limits
  60. GRB 260915A: NOT optical upper limit
  61. GRB 260915A: SVOM/VT optical upper limits from VHF data
  62. GRB 260915A: LCO optical upper limits
  63. GRB 260914A: EP-FXT follow-up observation
  64. GRB 260914A: LCO optical observation
  65. GRB 260914A: SVOM/C-GFT optical observations
  66. GRB 260914A: SVOM/VT optical counterpart confirmation
  67. GRB 260914A: SVOM/VT optical observation from VHF data
  68. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  69. GRB 260913A: SVOM/C-GFT optical upper limit
  70. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  71. GRB 260907A: SVOM/GRM observation
  72. GRB 260909A: CrAO and AbAO optical upper limits
  73. GRB 260910B: GOTO tentative optical counterpart candidates
  74. GRB 260909A: KAIT optical upper limit
  75. GRB 260903A: Swift-XRT observations
  76. EP260806a: VLA+ALMA radio detections
  77. GRB 260909A: VLT optical and near-infrared upper limits
  78. EP Alert 260909.53: Global MASTER-Net observations report
  79. GRB 260909A: EP-FXT follow-up observation
  80. GRB 260909A: SVOM/VT optical upper limits
  81. GRB 260909A: Mondy optical observations and afterglow candidate
  82. GRB 260909A: Xinglong 2.16m optical upper limit
  83. GRB 260909A: SVOM/C-GFT optical upper limit
  84. Fermi trigger No 810554827: Global MASTER-Net observations report
  85. EP Alert 260908.60: Global MASTER-Net observations report
  86. Fermi GRB 260907B: Global MASTER-Net observations report
  87. GRB 260903A: SAO RAS optical upper limit
  88. Fermi GRB 260907A: Global MASTER-Net observations report
  89. EP Alert 260905.11: Global MASTER-Net observations report
  90. GRB 260903A: J-band upper limit with WINTER
  91. EP Alert 260903.47: Global MASTER-Net observations report
  92. GRB260903A: Liverpool Telescope optical observations
  93. GRB 260903A: SAO RAS optical observations
  94. EP260903a: EP-WXT detection of a fast X-ray transient
  95. EP Alert 260903.62: Global MASTER-Net observations report
  96. GRB 260903A: OHP/T193 optical afterglow detection
  97. GRB 260903A: NOT optical observations and afterglow fading
  98. NuSTAR Transient 260828: SOAR Optical Upper Limits
  99. SVOM GRB260903A: Global MASTER-Net observations report
  100. GRB 260903A: LCO optical observations

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