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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"

3328 results found.

  1. EP250302a: Einstein Probe detection of an X-ray transient
  2. GRB 250226A: GRANDMA Optical Observations
  3. EP250302a: Montarrenti Observatory optical detection
  4. EP250302a: FTW optical and NIR detection
  5. EP250302a: Nanshan/HMT optical counterpart detection
  6. The EP-WXT trigger 01709132140 is likely a flaring star
  7. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  8. EP250228a: Optical observations with Kinder and Swift/UVOT
  9. Konus-Wind detection of GRB 250226A
  10. EP250227a: Global MASTER-Net observations report
  11. EP250223A: Upper limits from Fermi-GBM Observations
  12. EP250227a: TRT optical upper limit
  13. EP250227a: Optical upper limits with Kinder observations
  14. EP250227a: NOT optical observations
  15. EP250227a: Einstein Probe detected of a fast X-ray transient
  16. EP250228a: updates on the EP observations
  17. GRB 250226A: Fermi GBM Observation
  18. EP250225a: EP-FXT follow-up observation
  19. EP250223a: J band upper limit by SYSU 80cm telescope
  20. EP250228a: Swift/XRT localisation
  21. EP250228a: Global MASTER-Net observations report
  22. EP250228a: Einstein Probe detection of an X-ray transient
  23. GRB 250226A / EP250226a: LCO detection of the afterglow
  24. EP250226a/GRB 250226A: INTEGRAL SPI-ACS and PICsIT detection
  25. EP250225a: NOT optical candidate counterpart
  26. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  27. EP250225a: TRT optical upper limits
  28. EP250226a/GRB 250226A: Kinder optical follow-up observations
  29. Konus-Wind detection of GRB 250225B
  30. GRB 250226A: GECAM-B detection
  31. GRB 250221A: EP-FXT detection of the X-ray afterglow
  32. EP250226a/GRB 250226A: GSP detects optical counterpart
  33. EP250226a / GRB 250226A: TRT optical counterpart observation
  34. EP250226a: Global MASTER-Net observations report
  35. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  36. EP250225a: Global MASTER-Net observations report
  37. EP250225a: GSP optical upper limit
  38. EP250223a: GMG Optical Observation
  39. EP250225a: Einstein Probe detected of a fast X-ray transient
  40. EP250223a: GROWTH-India Telescope optical observations
  41. EP250215A: J band upper limit by SYSU 80cm telescope
  42. EP250223a: Kinder optical follow-up observations
  43. GRB 250219A: EP-FXT afterglow detection
  44. EP250223a: GOTO optical afterglow detections
  45. EP250223a: TRT optical afterglow observation
  46. EP250223a: refined analysis of the EP-WXT and FXT observations
  47. EP250223a: 1.6m Mephisto and 50cm array observations
  48. EP250223a: SVOM/VT optical observation
  49. The EP-WXT trigger 01709131882 is likely a flaring star
  50. EP250223a: OASDG optical observations
  51. EP250223a: LCO detection of the afterglow
  52. EP250223a: early optical detection by BOOTES-4
  53. EP250223a: NOT redshift z = 2.756
  54. EP250223a: Swift/XRT localization
  55. EP250223a: NOT optical afterglow candidate
  56. EP250223a: Global MASTER-Net observations report
  57. EP250223a: Einstein Probe detection of an X-ray transient
  58. Konus-Wind detection of GRB 250221A
  59. EP250220a: FTW optical and NIR observations and upper limits
  60. EP250220a: EP-FXT follow-up observations
  61. EP250220a: Liverpool Telescope upper limits
  62. EP250220a: 1.6m Mephisto observations
  63. EP250220a: Liverpool Telescope optical upper limits
  64. EP250220a: Optical upper limit with Kinder observations
  65. EP250220a: Xinglong optical upper limit
  66. EP250220a: Global MASTER-Net observations report
  67. EP250220a: EP-WXT detection of a fast X-ray transient
  68. Konus-Wind detection of GRB 250217C (short)
  69. Konus-Wind detection of GRB 250215A / EP250215a
  70. The EP-WXT trigger 01709131775 is likely a flaring star
  71. GRB 250215A / EP250215a: LCO detection of the afterglow
  72. EP250212a: FTW optical and NIR upper limits
  73. EP250215a / GRB 250215A : GTC redshift z = 4.61
  74. GRB 250215A: Fermi GBM Observation
  75. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  76. GRB 250215A / EP250215a: Gemini-South optical observation of a likely rebrightening
  77. GRB 250215A: Swift-XRT refined Analysis
  78. GRB 250215A: SVOM/GRM observation
  79. GRB 250215A / EP250215a: SVOM/VT optical candidate comfirmation
  80. EP250215a: Global MASTER-Net observations report
  81. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  82. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  83. EP250207b: Xinglong optical upper limit
  84. EP250212a: Xinglong optical upper limit
  85. EP250212a: Global MASTER-Net observations report
  86. EP250207B: Chandra localization of the X-ray counterpart
  87. EP250207b: VLA radio upper limits
  88. EP250212a: Liverpool Telescope optical upper limits
  89. EP250212a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  90. EP trigger 10202399251 (possibly EP250212a): NOT J-band upper limit
  91. EP250207B: GTC z-band Observations
  92. EP250207b: NOT optical counterpart candidate
  93. Konus-Wind detection of GRB 250207A
  94. Konus-Wind detection of GRB 250206A
  95. EP250207b: Liverpool Telescope possible optical counterpart
  96. EP250207b: Global MASTER-Net observations report
  97. Gemini-South spectroscopic redshift of EP250207b host galaxy candidate (z=0.082)
  98. EP250207b: Gemini GMOS-N z-band observations
  99. EP250207A: Upper limits from Fermi-GBM Observations
  100. EP250207b: a new X-ray transient detected by Einstein Probe

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