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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"

3379 results found.

  1. EP250223a: OASDG optical observations
  2. EP250223a: LCO detection of the afterglow
  3. EP250223a: early optical detection by BOOTES-4
  4. EP250223a: NOT redshift z = 2.756
  5. EP250223a: Swift/XRT localization
  6. EP250223a: NOT optical afterglow candidate
  7. EP250223a: Global MASTER-Net observations report
  8. EP250223a: Einstein Probe detection of an X-ray transient
  9. Konus-Wind detection of GRB 250221A
  10. EP250220a: FTW optical and NIR observations and upper limits
  11. EP250220a: EP-FXT follow-up observations
  12. EP250220a: Liverpool Telescope upper limits
  13. EP250220a: 1.6m Mephisto observations
  14. EP250220a: Liverpool Telescope optical upper limits
  15. EP250220a: Optical upper limit with Kinder observations
  16. EP250220a: Xinglong optical upper limit
  17. EP250220a: Global MASTER-Net observations report
  18. EP250220a: EP-WXT detection of a fast X-ray transient
  19. Konus-Wind detection of GRB 250217C (short)
  20. Konus-Wind detection of GRB 250215A / EP250215a
  21. The EP-WXT trigger 01709131775 is likely a flaring star
  22. GRB 250215A / EP250215a: LCO detection of the afterglow
  23. EP250212a: FTW optical and NIR upper limits
  24. EP250215a / GRB 250215A : GTC redshift z = 4.61
  25. GRB 250215A: Fermi GBM Observation
  26. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  27. GRB 250215A / EP250215a: Gemini-South optical observation of a likely rebrightening
  28. GRB 250215A: Swift-XRT refined Analysis
  29. GRB 250215A: SVOM/GRM observation
  30. GRB 250215A / EP250215a: SVOM/VT optical candidate comfirmation
  31. EP250215a: Global MASTER-Net observations report
  32. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  33. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  34. EP250207b: Xinglong optical upper limit
  35. EP250212a: Xinglong optical upper limit
  36. EP250212a: Global MASTER-Net observations report
  37. EP250207B: Chandra localization of the X-ray counterpart
  38. EP250207b: VLA radio upper limits
  39. EP250212a: Liverpool Telescope optical upper limits
  40. EP250212a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  41. EP trigger 10202399251 (possibly EP250212a): NOT J-band upper limit
  42. EP250207B: GTC z-band Observations
  43. EP250207b: NOT optical counterpart candidate
  44. Konus-Wind detection of GRB 250207A
  45. Konus-Wind detection of GRB 250206A
  46. EP250207b: Liverpool Telescope possible optical counterpart
  47. EP250207b: Global MASTER-Net observations report
  48. Gemini-South spectroscopic redshift of EP250207b host galaxy candidate (z=0.082)
  49. EP250207b: Gemini GMOS-N z-band observations
  50. EP250207A: Upper limits from Fermi-GBM Observations
  51. EP250207b: a new X-ray transient detected by Einstein Probe
  52. EP250207a: EP-WXT detection and XRT follow-up observation
  53. EP-WXT trigger 01709131361: correction to GCN 39214
  54. EP trigger 01709131361 (possible EP250207a): NOT optical observations and flaring star
  55. EP-WXT trigger 01709131361 / LIGO/Virgo/KAGRA S250206dm: FTW optical and NIR observations
  56. Konus-Wind detection of GRB 250204B
  57. LIGO/Virgo/KAGRA S250206dm: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  58. The EP-WXT trigger 01709131347 is likely a flaring star
  59. The EP-WXT trigger 01709131332 is likely a flaring star
  60. The EP-WXT trigger 01709131290 is likely a flaring star
  61. EP250205a/GRB 250205A: correction to the source localization
  62. EP250205a/GRB 250205A: Einstein Probe observation
  63. GRB 250205A: Redshift from OSIRIS+/GTC z = 3.55
  64. GRB 250205A: GOTO optical upper limits
  65. Konus-Wind detection of GRB 250201A
  66. Konus-Wind detection of GRB 250202B
  67. EP 250108A: Upper limits from Fermi-GBM Observations
  68. The EP-WXT trigger 01709131196 is likely a flaring star
  69. The EP-WXT trigger 01709131153 is not a real source
  70. Konus-Wind detection of GRB 250129A
  71. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  72. Ep250125A: 1.3m DFOT optical upper limit
  73. The EP-WXT trigger 01709131085: KAIT confirmation of the stellar flare
  74. GRB 250127A: CrAO and Terskol optical upper limits
  75. The EP-WXT trigger 01709131085 is likely a flaring star
  76. EP250125a: Upper limits from Swift/BAT-GUANO
  77. GRB 250127A: Swift-XRT observations
  78. GRB 250127A: EP-FXT afterglow detection
  79. EP250125A: Non-detection from Fermi-GBM Observations
  80. EP250108a / SN 2025kg: Refined Analysis of EP-WXT Detection
  81. EP250125a: Optical upper limit with Kinder observations
  82. EP250125a: REM optical counterpart detection
  83. EP250125a: Swift/XRT detection of a fading counterpart
  84. EP250125a: a new X-ray transient detected by Einstein Probe
  85. EP250125a: Gemini-South optical afterglow discovery and redshift z = 2.89
  86. The EP-WXT trigger 01709130758 is a false trigger
  87. The EP-WXT trigger 01709130758 is a false trigger
  88. Konus-Wind detection of a bright burst from SGR 1E1841-045 on 2025 January 23
  89. Konus-Wind detection of GRB 250118B
  90. Konus-Wind detection of GRB 250119B
  91. Konus-Wind detection of GRB 250117A
  92. EP250108a / SN2025kg: Non-detection from ATCA radio follow-up observations
  93. EP 250108A: Late-time optical observation by LCO
  94. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  95. EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
  96. EP250108a / AT 2025kg: the kangaroo is hopping, evidence for optical rebrightening
  97. EP250108a / AT2025kg: GMG Optical Observations
  98. Konus-Wind detection of GRB 250116A
  99. Konus-Wind detection of GRB 250113A
  100. EP250111a: SAO RAS optical upper limit

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