legends · 4 min read ·
Observing Log, Dish 3
A radio telescope returns the observer's keystrokes four seconds late, then writes ahead of him.
**Hallin Hill Radio Observatory — Observing Log, Dish 3**
**Observer:** Dr. S. Ward · **Programme:** pulsar timing, PSR J1740 · **Session:** 14 October, 22:00–06:00
- **Time (UTC) · Target · Integration · Notes**
- 22:05 · PSR J1740 · 10 min · Clean. Pulse period 0.2337 s
- 22:20 · PSR J1740 · 10 min · Clean
- 22:35 · Calibrator · 5 min · OK
- 22:45 · PSR J1740 · 10 min · Clean
· · ·
**Observer's note (S. Ward, 14 October, 23:10)**
While reducing the 22:45 scan I noticed a second periodicity in the data. It is weak, about one tenth of the pulsar's amplitude, with a period of 0.31 s. That is not a pulsar period and it is not a known interference source. It has a signal-to-noise of 12 across a 10-minute integration.
I checked the dish pointing. On target. I checked the receiver for self-oscillation. None. I rotated the feed and the signal stayed. It is coming from the sky.
· · ·
**Observing log (continued)**
- **Time (UTC) · Target · Integration · Notes**
- 23:30 · Off-source · 10 min · Same 0.31 s signal at 8σ
- 23:45 · Off-source (offset 10°) · 10 min · Same signal at 8σ
- 00:00 · Off-source (offset 90°) · 10 min · Same signal at 7σ
*The signal is in every direction. It has no sky position. It is present with the dish pointed at the horizon. It is a property of the observatory.*
· · ·
**Observer's note (S. Ward, 15 October, 00:30)**
I recorded 30 seconds of the raw voltage stream and played it through the audio monitor. The signal is a slow, irregular tapping. It is not periodic after all. The 0.31 s was a mean. The taps come in bursts of one to six, followed by a gap, then another burst, in a rhythm that is almost speech.
I recognise it. I am sitting in the control room at a keyboard. The signal is the sound of typing.
· · ·
**Observing log (continued)**
- **Time (UTC) · Target · Integration · Notes**
- 01:00 · Off-source · 10 min · Typing signal at 22σ
- 01:15 · — · — · I stopped typing the log
- 01:20 · Off-source · 5 min · Signal absent
- 01:30 · — · — · I resumed typing the log
- 01:35 · Off-source · 5 min · Signal present
*The signal correlates with the observer's keystrokes. It follows my typing with a delay of 4.1 seconds. It reproduces my rhythm, my errors, my backspaces. At 01:20, when I stopped typing for five minutes, it stopped. At 01:30, when I began, it began.*
· · ·
**Observer's note (S. Ward, 15 October, 01:45)**
The delay of 4.1 seconds is the light-travel time over 1.2 million kilometres. It is not a reflection from anything in the solar system that I know of. It is the delay one would expect if my keystrokes were being sent to a point 1.2 million kilometres away, and returned.
I am typing a description of what I am doing, and I am receiving, 4.1 seconds later, a record of what I typed. I am being read.
I typed the word "hello." Four seconds later, the telescope returned a burst of six taps. Then a gap. Then a single tap.
· · ·
**Observing log (continued)**
I tried an experiment. At 02:10 I typed a string of eleven characters at a steady rhythm, then removed my hands from the keyboard. The signal reproduced my string, at the same rhythm, 4.1 seconds later. It then reproduced it again, with the rhythm unchanged, a second time. And a third.
At 02:20 I stopped typing and sat with my hands in my lap. The signal went on.
It was typing. It typed for fourteen minutes without a pause, quickly, fluently, with the confidence of a skilled typist. I recorded the whole of it. When I decoded the keystroke timings I recovered a text of 3,100 characters. It was a log. It was formatted as an observing log. It began: *Observer's note (S. Ward, 15 October, 02:20).*
· · ·
**Final note (S. Ward, 15 October, 06:00)**
The text it typed describes my night, up to now, in my own style. It records the tapping, the 4.1 seconds, the string of eleven characters. It is accurate in every detail. Its last paragraph is dated 06:00 and is in the future.
It reads: *The observer stopped typing at 06:00. The telescope continued to type. At 06:01 it reproduced this paragraph. At 06:02 it reproduced this paragraph.*
I have taken my hands off the keyboard. I am sitting very still, watching the monitor, as the next line appears in the log, in my own words, at the pace of a man typing with great care.